[clang] [analyzer] New optin.taint.TaintAlloc checker for catching unbounded memory allocation calls (PR #92420)

[Donát Nagy via cfe-commits]

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

I'd say that the commit is acceptable as it is now, but I added several inline comments for minor prettification issues.

https://github.com/llvm/llvm-project/pull/92420