[clang] [analyzer][NFC] Introduce framework for checker families (PR #139256)

[Donát Nagy via cfe-commits]

NagyDonat wrote:

Thanks for your understanding – and sorry for stretching this review process for so long.

I will push and merge the reduced commit on Monday (to be able to follow up its effect in the CI). I will probably also create a spinoff PR that contains some minor NFC code quality improvements (introducing `addMockChecker`, adding comments) for the `CodeRegistry` areas.

https://github.com/llvm/llvm-project/pull/139256