[llvm] [SPIRV] Emitting DebugSource, DebugCompileUnit (PR #97558)

[Michal Paszkowski via llvm-commits]

michalpaszkowski wrote:

@bwlodarcz Would it be possible to add a couple LIT tests demonstrating the currently expected behavior? You could create a new directory for the DebugInfo tests.

Also, if you think it would be beneficial for the development of this pass and to definitely make debugging easier, you could [follow the tests for the SPIRVEmitIntrinsics](https://github.com/llvm/llvm-project/blob/main/llvm/test/CodeGen/SPIRV/passes/SPIRVEmitIntrinsics-TargetExtType-arg-no-spv_assign_type.ll) and create some LITs which would verify just the output of this pass using `-print-after-all` and  `CHECK` line with the pass name,

https://github.com/llvm/llvm-project/pull/97558