[clang] [analyzer] Unbreak [[clang::suppress]] on checkers without decl-with-issue. (PR #79398)

[Artem Dergachev via cfe-commits]

haoNoQ wrote:

The affected checkers were:
- Checkers in the `webkit` package (hence cc @jkorous-apple). These checkers manually scan the entire TU in order (rejecting the comforts of `checkASTCodeBody`) in order to properly cover uninstantiated templates. There's no reason they can't provide a decl-with-issue but it's often annoying to detect.
- Copy-paste error checkers. Again, the checker can provide decl-with-issue, but plumbing gets quite annoying. The test case is super funny though!

https://github.com/llvm/llvm-project/pull/79398