[clang] [clang-tools-extra] [llvm] [clang] Introduce diagnostics suppression mappings (PR #112517)

[Boaz Brickner via llvm-commits]

================

----------------
bricknerb wrote:

Given that Test documentation build check failed, it's worth clarifying how the documentation was tested and perhaps add a few screenshots.

https://github.com/llvm/llvm-project/pull/112517