[llvm] [ABI][AMDGPU] Add AMDGPU target ABI classifier to the LLVM ABI library (PR #220177)

[via llvm-commits]

skc7 wrote:

> Can you also add Clang tests that check function signatures with and without the ABI library?

This PR covers AMDGPU classifier and unit tests, so nothing emits a CIR signature to check yet. Those with/without-ABI-library signature tests belong in the wiring PR #220197, which drives this classifier from `CallConvLowering` and already carries the abi-lowering/*.cir FileCheck tests, It is still WIP and I'll make sure the with/without parity is covered there.

https://github.com/llvm/llvm-project/pull/220177