[llvm] [llvm-calc-occupancy] Add an AMDGPU occupancy calculator tool (PR #208727)

[via llvm-commits]

michaelselehov wrote:

The fix is in https://github.com/llvm/llvm-project/pull/213023 - auto-merge enabled, will land as soon as the checks are done.

https://github.com/llvm/llvm-project/pull/208727