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

[Boaz Brickner via cfe-commits]

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bricknerb wrote:

Unit tests cover the code and Clang integration tests are useful to test a feature end-to-end.
The compiler logic that handles the code until it reaches this point might break the assumptions we have in the specific code (especially if we think about future changes to the logic).

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