[clang] [llvm] [HLSL] Add SPIR-V version of getPointer. (PR #121963)

[Nathan Gauër via llvm-commits]

https://github.com/Keenuts approved this pull request.

Maybe the renaming shall be done in another PR for both DXIL and SPV, but if it's a small change, might want to do it now no?

https://github.com/llvm/llvm-project/pull/121963