[llvm] [AMDGPU] Add alignment attr & propagate alignment through make.buffer.rsrc inst (PR #145278)

[Krzysztof Drewniak via llvm-commits]

https://github.com/krzysz00 commented:

This seems reasonable overall though i'll leave final review to folks familiar with the attributor.

One question: how much work would it be to materialize the returned alignment as a attribute on the `make.buffer.rsrc` call? I figure it'll help make it more obvious what's going on.

https://github.com/llvm/llvm-project/pull/145278