[clang] [CIR][SPIR-V] Move global address space selection to a target hook (PR #231098)

[Steffen Larsen via cfe-commits]

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

I think this makes sense, but it might be good to get codeowner thoughts too.

https://github.com/llvm/llvm-project/pull/231098