Implement getAsyncInfo in ILCompiler

[jtschuster]

Updates the definition of CORINFO_ASYNC_INFO to match CoreCLRs definition, and adds an implementation for the getAsyncInfo jit callback in ReadyToRun.

[Copilot]

Pull Request Overview

This PR implements the getAsyncInfo callback in the ILCompiler's JIT interface to support async method compilation in ReadyToRun scenarios. The implementation aligns with CoreCLR's definition by expanding the CORINFO_ASYNC_INFO structure and providing concrete field and method handle lookups.

Key Changes:

• Extended CORINFO_ASYNC_INFO structure with additional fields for async state management
• Implemented the getAsyncInfo method to populate async continuation and context management handles
• Added support for execution context capture/restore operations in async workflows

Reviewed Changes

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

File	Description
src/coreclr/tools/Common/JitInterface/CorInfoTypes.cs	Extended CORINFO_ASYNC_INFO structure with new fields for Resume, State, Flags, execution context methods, and continuation context handling
src/coreclr/tools/Common/JitInterface/CorInfoImpl.cs	Implemented getAsyncInfo method to populate async info structure with handles for Continuation class fields and AsyncHelpers methods

[jkotas]

This will change a bit after #120411

cc @jakobbotsch

[VSadov]

Yes, the shape of the info will change with "flat continuations".

[jakobbotsch]

I merged #120411 so as pointed out above the shape of CORINFO_ASYNC_INFO changed a bit.

[jakobbotsch]

Needs to be adapted to #120411