[clang] [Clang][AMDGPU] Add builtins for instrinsic `llvm.amdgcn.raw.buffer.store` (PR #94576)

[Matt Arsenault via cfe-commits]

arsenm wrote:

> `voffset` and `soffset` are "offset that goes in VGPRs" and "offset that goes in SGPRs", with the latter having some different bounds-checking semantics on ... at least some of the gfx9's, IIRC.
> 

Right, that's the problem. We need to know the parameters of the SRD in order to make use of the scalar offset. Ideally we would have one pointer operand and be able to addressing mode match into soffset/voffset/imm 

https://github.com/llvm/llvm-project/pull/94576