[clang] [analyzer][NFC] Reorg and add clang::suppress tests (PR #186447)

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat approved this pull request.

Thank you very much for creating this big and complex PR! This is exactly what I had in mind when I reviewed your previous PR https://github.com/llvm/llvm-project/pull/183727 .

I read all the new tests and thanks to the separators and logical groupings it was easy to see their purpose and "place". I spotted a few minor inconsistencies (marked with inline comments), but overall the code quality is great, I would probably make more mistakes if I had to write something similar.

The commit LGTM if you handle those minor remarks.

https://github.com/llvm/llvm-project/pull/186447