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

[Donát Nagy via cfe-commits]

https://github.com/NagyDonat commented:

It's good to see that this checker is finished. I added several inline comments, but they are not serious issues -- most are connected to `CallDescription`s where I'm now very familiar with the available options (and I refactored the code, so others are not so familiar with it...).

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