Add test for non-async generic methods mismatch in ILC scanner/JIT

[eduardo-vp]

Adding test for #127179.

ILC crashes when trying to compile a runtime async method on a generic type that calls a non-async generic method. The JIT tries to use the async call method whereas the scanner only generated information for the thunk.

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[Copilot]

Pull request overview

Adds a new async regression test intended to cover #127179 by exercising a generic async ValueTask<T> method awaiting a non-async generic method, targeting an ILC scanner vs JIT expectation mismatch scenario.

Changes:

• Introduces a new test project under src/tests/async/awaitingnoasyncgeneric/ using Microsoft.NET.Sdk.IL.
• Adds a simple xUnit test that runs the pattern for both reference and value generic instantiations.
• Forces optimization on in the test project to ensure the relevant scanning/codegen path is exercised.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/tests/async/awaitingnoasyncgeneric/awaitingnoasyncgeneric.csproj	New test project with optimization + process isolation settings.
src/tests/async/awaitingnoasyncgeneric/awaitingnoasyncgeneric.cs	New xUnit test and minimal repro pattern using generic ValueTask<T>.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[MichalStrehovsky]

For the actual fix, I think we can start with a PR that gets rid of the guessing in ILScanner (the spot where we try to figure out whether to use the runtime async or non-runtime async entrypoint) - just report both dependencies. Once we have a PR doing that, we can do a measurement with https://github.com/MichalStrehovsky/rt-sz and take it from there.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.