[HLSL] Rich availability diagnostics

[llvm-beanz]

Description

Each new shader model introduces new APIs that expose new hardware and runtime functionality. We should provide diagnostics to users about API availability notifying them when they use APIs that are not available.

A detailed design proposal for the Clang implementation is available here:
https://github.com/microsoft/hlsl-specs/blob/main/proposals/infra/INF-0001-availability-diagnostics.md

Acceptance Criteria

• [INF-0001] Rework and finalize diagnostic text microsoft/hlsl-specs#188
• [INF-0001] Consider environment as a parameter to availability attribute microsoft/hlsl-specs#189
• [Clang][HLSL] Add environment parameter to Clang availability attribute #89802
• [HLSL] Implement availability diagnostic - Default and Relaxed modes #90095
• [HLSL] Implement availability diagnostic - Strict mode #90096
• [HLSL] Enable HLSL availability diagnostic on exported library functions and add tests #92073

[llvm-beanz]

@hekota is going to be taking this over

[hekota]

I will take this.