…tura.AssemblyLoader (#5910)

For automatic instrumentation, the tracer inserts a startup hook inside the first method that we deem as a "valid" startup hook callsite. This change adds logic so that methods inside the `Costura.AssemblyLoader` type are not "valid" startup hook callsites, so that the insertion of the startup hook can be delayed to a later method call.

…stura.AssemblyLoader` (#5910 -> v2) (#5934)

## Summary of changes
For automatic instrumentation, the tracer inserts a startup hook inside
the first method that we deem as a "valid" startup hook callsite. This
change adds logic so that methods inside the `Costura.AssemblyLoader`
type are not "valid" startup hook callsites, so that the insertion of
the startup hook can be delayed to a later method call.

## Reason for change
We've seen a case where a WCF client application uses
[Costura.Fody](https://github.com/Fody/Costura), and when
instrumentation is added to the application it begins running into
assembly loading issues with the following exception:

```
System.Configuration.ConfigurationErrorsException: Configuration binding extension 'system.serviceModel/bindings/basicHttpsBinding' could not be found. Verify that this binding extension is properly registered in system.serviceModel/extensions/bindingExtensions and that it is spelled correctly. (C:\scratch\APMS-00000\WcfServiceLibrary1\GettingStartedClient\bin\Debug\GettingStartedClient.exe.Config line 8)

   at System.Configuration.BaseConfigurationRecord.EvaluateOne(String[] keys, SectionInput input, Boolean isTrusted, FactoryRecord factoryRecord, SectionRecord sectionRecord, Object parentResult) in System.Configuration\BaseConfigurationRecord.cs:line 1379
   at System.Configuration.BaseConfigurationRecord.Evaluate(FactoryRecord factoryRecord, SectionRecord sectionRecord, Object parentResult, Boolean getLkg, Boolean getRuntimeObject, Object& result, Object& resultRuntimeObject) in System.Configuration\BaseConfigurationRecord.cs:line 1314
   at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject) in System.Configuration\BaseConfigurationRecord.cs:line 1157
   at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject) in System.Configuration\BaseConfigurationRecord.cs:line 1157
   at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(String configKey, Boolean getLkg, Boolean checkPermission, Boolean getRuntimeObject, Boolean requestIsHere, Object& result, Object& resultRuntimeObject) in System.Configuration\BaseConfigurationRecord.cs:line 1157
   at System.Configuration.BaseConfigurationRecord.GetSection(String configKey, Boolean getLkg, Boolean checkPermission) in System.Configuration\BaseConfigurationRecord.cs:line 1000
   at System.Configuration.BaseConfigurationRecord.GetSection(String configKey) in System.Configuration\BaseConfigurationRecord.cs:line 579
   at System.Configuration.ClientConfigurationSystem.System.Configuration.Internal.IInternalConfigSystem.GetSection(String sectionName) in System.Configuration\ClientConfigurationSystem.cs:line 179
   at System.Configuration.ConfigurationManager.GetSection(String sectionName) in System.Configuration\ConfigurationManager.cs:line 171
   at System.ServiceModel.Activation.AspNetEnvironment.UnsafeGetSectionFromConfigurationManager(String sectionPath) in System.ServiceModel.Activation\AspNetEnvironment.cs:line 210
   at System.ServiceModel.Activation.AspNetEnvironment.UnsafeGetConfigurationSection(String sectionPath) in System.ServiceModel.Activation\AspNetEnvironment.cs:line 198
   at System.ServiceModel.Configuration.ConfigurationHelpers.UnsafeGetAssociatedSection(ContextInformation evalContext, String sectionPath) in System.ServiceModel.Configuration\ConfigurationHelpers.cs:line 141
   at System.ServiceModel.Configuration.ConfigurationHelpers.UnsafeGetSection(String sectionPath) in System.ServiceModel.Configuration\ConfigurationHelpers.cs:line 194
   at System.ServiceModel.Configuration.ClientSection.UnsafeGetSection() in System.ServiceModel.Configuration\ClientSection.cs:line 49
   at System.ServiceModel.Description.ConfigLoader.LookupChannel(ContextInformation configurationContext, String configurationName, ContractDescription contract, EndpointAddress address, Boolean wildcard, Boolean useChannelElementKind, ServiceEndpoint& serviceEndpoint) in System.ServiceModel.Description\ConfigLoader.cs:line 1034
   at System.ServiceModel.Description.ConfigLoader.LookupEndpoint(String configurationName, EndpointAddress address, ContractDescription contract, ContextInformation configurationContext) in System.ServiceModel.Description\ConfigLoader.cs:line 495
   at System.ServiceModel.Description.ConfigLoader.LookupEndpoint(String configurationName, EndpointAddress address, ContractDescription contract) in System.ServiceModel.Description\ConfigLoader.cs:line 488
   at System.ServiceModel.ChannelFactory.InitializeEndpoint(String configurationName, EndpointAddress address) in System.ServiceModel\ChannelFactory.cs:line 359
   at System.ServiceModel.ChannelFactory`1..ctor(String endpointConfigurationName, EndpointAddress remoteAddress) in System.ServiceModel\ChannelFactory.cs:line 653
   at System.ServiceModel.ChannelFactory`1..ctor(String endpointConfigurationName) in System.ServiceModel\ChannelFactory.cs:line 632
   at System.ServiceModel.ConfigurationEndpointTrait`1.CreateSimplexFactory() in System.ServiceModel\ConfigurationEndpointTrait.cs:line 78
   at System.ServiceModel.ConfigurationEndpointTrait`1.CreateChannelFactory() in System.ServiceModel\ConfigurationEndpointTrait.cs:line 60
   at System.ServiceModel.ClientBase`1.CreateChannelFactoryRef(EndpointTrait`1 endpointTrait) in System.ServiceModel\ClientBase.cs:line 1755
   at System.ServiceModel.ClientBase`1.InitializeChannelFactoryRef() in System.ServiceModel\ClientBase.cs:line 1749
   at System.ServiceModel.ClientBase`1..ctor() in System.ServiceModel\ClientBase.cs:line 1088
   at GettingStartedClient.ServiceReference1.CalculatorClient..ctor() in C:\scratch\APMS-00000\WcfServiceLibrary1\GettingStartedClient\Connected Services\ServiceReference1\Reference.cs:line 51
   at GettingStartedClient.Program.Main(String[] args) in C:\scratch\APMS-00000\WcfServiceLibrary1\GettingStartedClient\Program.cs:line 21
```

The issue, it appears, is that the Datadog tracing startup hook is being
inserted into either the `Costura.AssemblyLoader..cctor()` or the
`Costura.AssemblyLoader.Attach()` methods, which Costura adds into the
module initializer of the target assembly. These methods add an
AssemblyResolve event handler so that the application can load dependent
assemblies from the assembly resources, since they are no longer on
disk. Since the tracing startup hook also adds an AssemblyResolve event
handler, I experimented with delaying the startup hook insertion so that
the Costura AssemblyResolve event handler would be added first and
it....worked.

## Implementation details
Adds more logic to the startup hook logic to check against the
`Costura.AssemblyLoader` type when considering if a callsite is valid
for startup hook insertion.

## Test coverage
I was able to reproduce the issue by:
- Setting up a WCF client application and WCF server application using
the following [Getting
Started](https://learn.microsoft.com/en-us/dotnet/framework/wcf/getting-started-tutorial)
tutorial
- Updating endpoint with `binding=basicHttpsBinding` (and using a port
on my machine with proper HTTPS permissions)
- Adding the `Costura.Fody` v4.0.0 NuGet package to the client
application with an empty FodyWeavers.xml
```
<Weavers>
  <Costura/>
</Weavers>
```
- Running the WCF client application
- Add Datadog .NET automatic instrumentation

Before the changes, the application would crash with the above error.
After the changes, the application runs without issue.

If needed, I can check in a smoke test but to avoid repository bloat I
figured the step-by-step above would be sufficient.

## Other details

Internal ticket: APMS-12728
Backporting #5910 from 3.x to 2.x

Co-authored-by: Zach Montoya <[email protected]>