.Net Processes - Add Process-Level Error Handler - #9477

Motivation and Context

Enabled support for function-specific error-handler step in this PR: #9187

Fixes: #9291

This change provides the ability to define a process scoped error handler (as opposed to function specific).

When a function-scoped error-handler is defined, it will take precedence.

Description

ProcessBuilder process = new(nameof(ProcessFunctionErrorHandledAsync));

ProcessStepBuilder errorStep = process.AddStepFromType<ErrorStep>();
process.OnError().SendEventTo(new ProcessFunctionTargetBuilder(errorStep));

class ErrorStep : KernelProcessStep
{
    [KernelFunction]
    public void GlobalErrorHandler(Exception exception) { }
}

Notes:

• Switch error handler from passing Exception object to a KernelProcessError to satisfy serialization expectations
• Normalized namespaces for Internal shared code
• Introduced shared ProcessConstants file
• Opportunistically converted some List creation to Array
• Opportunistically included parameter name in some Verify assertions.
• Opportunistically removed a extraneous not-null directives (!)
• Verified DAPR error handling in demo app (True means the expected error handler was invoked):

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the SK Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄