[llvm] [SPIRV] Add definitions for NonSemantic debug info (PR #95530)

[Nathan Gauër via llvm-commits]

Keenuts wrote:

Hi @bwlodarcz, LGTM.
In case you missed it, to properly implement debug info on class+methods, you'll need this extension:
 https://htmlpreview.github.io/?https://github.com/KhronosGroup/SPIRV-Registry/blob/main/extensions/KHR/SPV_KHR_relaxed_extended_instruction.html

https://github.com/llvm/llvm-project/pull/95530