[clang] [clang][analyzer] Add checker 'security.SetgidSetuidOrder'. (PR #91445)

[Endre Fülöp via cfe-commits]

https://github.com/gamesh411 approved this pull request.

Emitting a note to the location where the first part of the detected pattern (the `setuid(getuid())` call) seems like useful information, but this patch is great as it is.
You could also add it in another patch if it is not trivial.

https://github.com/llvm/llvm-project/pull/91445