[llvm] [SPIR-V] Add pre-commit CI workflow (PR #74092)

[Natalie Chouinard via llvm-commits]

sudonatalie wrote:

> If it worked, when you compare the phase2.stats and phase3.stats output it should should mostly an increase in the Hits category. I did this test locally and it appears that adding -DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD:STRING=SPIRV does not invalidate the cache, which is good, but the SPIRV backend failed to build, so you might want to double check my work here.

Looks the same for me and the build succeeded.

https://github.com/llvm/llvm-project/pull/74092