[llvm] [SPIR-V] Add pass to remove spv_ptrcast intrinsics (PR #128896)

[Steven Perron via llvm-commits]

https://github.com/s-perron commented:

In general, this looks good. I just have some minor tweaks. The main thing is that the focus of the pass should be to remove pointer casts. The loads themselves are fine. We may also need to fix stores, and possibly other types of uses. We should rename the pass to reflect that.

https://github.com/llvm/llvm-project/pull/128896