[NativeAOT] Delegate bug fixes

[jkotas]

• Fix Delegate.Method and Delegate.Target for marshalled delegates
• Add tests and fixes for corner various delegate corner case behaviors
• Delete runtime test for GetInvocationList since there is a better test coverage for this API under libraries

Fixes dotnet/runtimelab#164

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Issue Details

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• Fix Delegate.Method and Delegate.Target for marshalled delegates
• Add tests and fixes for corner various delegate corner case behaviors
• Delete runtime test for GetInvocationList since there is a better test coverage for this API under libraries

Fixes dotnet/runtimelab#164

Author:	jkotas
Assignees:	jkotas
Labels:	area-Meta
Milestone:	-

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Tagging subscribers to this area: @agocke, @MichalStrehovsky, @jkotas
See info in area-owners.md if you want to be subscribed.

Issue Details

---

• Fix Delegate.Method and Delegate.Target for marshalled delegates
• Add tests and fixes for corner various delegate corner case behaviors
• Delete runtime test for GetInvocationList since there is a better test coverage for this API under libraries

Fixes dotnet/runtimelab#164

Author:	jkotas
Assignees:	jkotas
Labels:	area-Meta, area-NativeAOT-coreclr
Milestone:	-

[AustinWise]

While reviewing I noticed the PInvokeDelegateThunk class may be finalized before the delegate is fully collected. This causes this program to crash on NativeAOT:

https://gist.github.com/AustinWise/87eb03c4ec0cd06564c79e9b33bcfc07

One possible fix: make GCHandle in PInvokeDelegateThunk be WeakTrackResurrection. In the PInvokeDelegateThunk finalizer check to see if the object pointed to by the handle is still alive. If so, call ReRegisterForFinalize to defer finalization.

[jkotas]

/azp run runtime-nativeaot-outerloop

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[jkotas]

While reviewing I noticed the PInvokeDelegateThunk class may be finalized before the delegate is fully collected

@AustinWise Thank you! I have included the fix and the test in this PR.

[jkotas]

/azp run runtime-nativeaot-outerloop

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Azure Pipelines successfully started running 1 pipeline(s).

[jkotas]

This is ready for review

[jkotas]

/azp run runtime-nativeaot-outerloop

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Azure Pipelines successfully started running 1 pipeline(s).

[MichalStrehovsky]