…utableDirectLogSubmissionSettings` (#6400)

## Summary of changes

Merge `DirectLogSubmissionSettings` with
`ImmutableDirectLogSubmissionSettings`

## Reason for change

There was never really a good reason for having these as separate types.
It was primarily to make testing a little easier and to mirror the
`TracerSettings`/`ImmutableTracerSettings` dichotomy, but as that's
going away, this is just unnecessary complexity

## Implementation details

- Moved the additional logic that was previously inside
`ImmutableDirectLogSubmissionSettings` into
`DirectLogSubmissionSettings`
- Renamed the `DirectLogSubmissionSettings` properties to match the
"Immutable" version (and remove the unnecessary prefix)
- Replace all usages of `Immutable*` with `DirectLogSubmissionSettings`
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization (using `IConfigurationSource`)

## Test coverage

Essentially the same. I removed/tweaked some tests that are no longer
relevant

## Other details

Part of stack

- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399
- #6400  👈 This PR
- #6405
- #6408
- #6415

…tegrationSettings` (#6405)

## Summary of changes

Merge `IntegrationSettings` with `ImmutableIntegrationSettings`

## Reason for change

This stack of PRs is about doing one-shot configuration instead of
mutation. We never mutate these in the tracer after creation, so there's
no need for the separate types.

## Implementation details

- Moved additional logic (handling `DisabledNames` that was previously
inside `ImmutableIntegrationSettings` into `IntegrationSettings`
- Replace all usages of `Immutable*` with `IntegrationSettings`
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization
- Reorder initialization of `DisabledIntegrationNames` in
`TracerSettings` so that it can be used in the `IntegrationSettings`
constructor

## Test coverage

All covered by existing details

## Other details

Part of Stack
- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399
- #6400
- #6405 👈 This PR
- #6408
- #6415

…terSettings` (#6408)

## Summary of changes

Merge `ExporterSettings` with `ImmutableExporterSettings`

## Reason for change

This stack of PRs is about doing one-shot configuration instead of
mutation. We never mutate these in the tracer after creation, so there's
no need for the separate types.

## Implementation details

- Made the properties in `ExporterSettings` get-only. This required
quite a lot of work because we were doing a lot of mutating of the
settings in the "helper" functions.
- I only _lightly_ refactored those methods (as much as possible) to
avoid setting the properties in the functions and instead returning the
details to set later.
- These are prime candidates for some _much_ heavier refactoring later,
but I didn't want to get bogged down with that in this PR
- Replace all usages of `Immutable*` with `ExporterSettings`
- Replace usages of `AgentUriInternal` with `AgentUri`
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization

## Test coverage

All covered by existing details

## Other details

Part of Stack
- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399
- #6400
- #6405
- #6408 👈 This PR
- #6415

…utableDirectLogSubmissionSettings` (#6400)

## Summary of changes

Merge `DirectLogSubmissionSettings` with
`ImmutableDirectLogSubmissionSettings`

## Reason for change

There was never really a good reason for having these as separate types.
It was primarily to make testing a little easier and to mirror the
`TracerSettings`/`ImmutableTracerSettings` dichotomy, but as that's
going away, this is just unnecessary complexity

## Implementation details

- Moved the additional logic that was previously inside
`ImmutableDirectLogSubmissionSettings` into
`DirectLogSubmissionSettings`
- Renamed the `DirectLogSubmissionSettings` properties to match the
"Immutable" version (and remove the unnecessary prefix)
- Replace all usages of `Immutable*` with `DirectLogSubmissionSettings`
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization (using `IConfigurationSource`)

## Test coverage

Essentially the same. I removed/tweaked some tests that are no longer
relevant

## Other details

Part of stack

- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399
- #6400  👈 This PR
- #6405
- #6408
- #6415

…tegrationSettings` (#6405)

## Summary of changes

Merge `IntegrationSettings` with `ImmutableIntegrationSettings`

## Reason for change

This stack of PRs is about doing one-shot configuration instead of
mutation. We never mutate these in the tracer after creation, so there's
no need for the separate types.

## Implementation details

- Moved additional logic (handling `DisabledNames` that was previously
inside `ImmutableIntegrationSettings` into `IntegrationSettings`
- Replace all usages of `Immutable*` with `IntegrationSettings`
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization
- Reorder initialization of `DisabledIntegrationNames` in
`TracerSettings` so that it can be used in the `IntegrationSettings`
constructor

## Test coverage

All covered by existing details

## Other details

Part of Stack
- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399
- #6400
- #6405 👈 This PR
- #6408
- #6415

…terSettings` (#6408)

## Summary of changes

Merge `ExporterSettings` with `ImmutableExporterSettings`

## Reason for change

This stack of PRs is about doing one-shot configuration instead of
mutation. We never mutate these in the tracer after creation, so there's
no need for the separate types.

## Implementation details

- Made the properties in `ExporterSettings` get-only. This required
quite a lot of work because we were doing a lot of mutating of the
settings in the "helper" functions.
- I only _lightly_ refactored those methods (as much as possible) to
avoid setting the properties in the functions and instead returning the
details to set later.
- These are prime candidates for some _much_ heavier refactoring later,
but I didn't want to get bogged down with that in this PR
- Replace all usages of `Immutable*` with `ExporterSettings`
- Replace usages of `AgentUriInternal` with `AgentUri`
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization

## Test coverage

All covered by existing details

## Other details

Part of Stack
- #6370
- #6376
- #6385
- #6386
- #6397 
- #6399
- #6400
- #6405
- #6408 👈 This PR
- #6415

…ettings` (#6415)

Merge `TracerSettings` with `ImmutableTracerSettings`

This stack of PRs is about doing one-shot configuration instead of
mutation. We never mutate these in the tracer after creation, so there's
no need for the separate types.

- Make the properties in `TracerSettings` get-only.
- Make the collections in `TracerSettings` readonly.
- Move logic that used to be in the constructor of
`ImmutableTracerSettings` into `TracerSettings`
- e.g. Service/Version/Env were being changed based on DD_TAGS values.
Moved that to TracerSettings and (importantly) added missing telemetry
recording of these values.
  - Added missing recording of _effective_ `DisabledInstegrations`
- Moving this logic caused some _tests_ to be broken (checking default
values). Updated the expected values of those tests in a single
- Replace all usages of `ImmutableTracerSettings` with `TracerSettings`
- Move `ITracer` to Datadog.Trace.Manual
- It's only used there, and references the manual-version of
`ImmutableTracerSettings` which we _want_ to keep.
- Move `Immutable*Tests` into appropriate file and tweak
- Replace mutations with initialization in tests

All covered by existing tests (I hope) 🤞

There's still a _lot_ of scope to improve this

Part of Stack
- #6370
- #6376
- #6385
- #6386
- #6397
- #6399
- #6400
- #6405
- #6408
- #6415 👈 This PR