[llvm] [SPIR-V] Add legalize-addrspace-cast pass (PR #137598)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

Thanks a lot @Naghasan , looks like this is what we needed in the end. Opened https://github.com/llvm/llvm-project/pull/137766 and closing this one.

https://github.com/llvm/llvm-project/pull/137598