TypeSystem: Support ref structs within generics

[mangod9]

This is a top-level issue to track supporting ref structs within generics. For additional details refer to dotnet/csharplang#7608 and the older dotnet/csharplang#1148.

• Finish support for ref fields - ref field support in .NET runtimes #63768
• Get design approval from all stakeholders
  • Design to support ByRefLike types in Generics #67129
  • Support for ref struct as generic arguments csharplang#5689
  • Allow ref struct to implement interfaces csharplang#7625
  • Managed API [API Proposal]: Add managed API surface area for ByRefLike Generic constraints #68002
• Enable CoreCLR Support
  • Support ByRefLike types as Generic parameters #67783
  • Support may equivalence - see Type test for ref struct is incorrect roslyn#63085
• .NET API for "is-type" scenarios - [API Proposal]: Methods to support ByRefLike types in "is-type" IL sequences #105435
• [Mono] Enable support for IsByRefLike types in generics #94415
  • Support gpAcceptByRefLike metadata generic param attribute
  • JIT+AOT boxing elision support; generic sharing support
  • Interp boxing elision support
• Update ECMA-335 - Update docs for ByRefLike with generics for work in .NET 10 #103318
• Add Test cases and Functional Validation
• R2R Support
• Allow ref structs to implement interfaces
  • CoreCLR - Disallow ref structs to use DIM implementations - CoreCLR NativeAOT - ByRef generics and ByRef implementing interfaces #98070
  • Mono - Disallow ref structs to use DIM implementations
• Update System.Activator.CreateInstance<T>() to include the allows ref struct constraint.
  • This will need to be done in all runtimes. - Activator.CreateInstance supports ByRefLike types #102636
• Cecil/trimmer support for ref structs within generics

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[mangod9]

@AaronRobinsonMSFT , assume this is ok to close or is there more work required here?