[clang] [clang-tools-extra] [clang-tidy][dataflow] Add `bugprone-null-check-after-dereference` check (PR #84166)

[Piotr Zegar via cfe-commits]

PiotrZSL wrote:

> I think those issues are stale.
Last time I tested it it were on Clang-tidy 17. I'm doing migration to Clang-tidy 18 now. I will check this and bugprone-unchecked-optional-access check on my code-base, on which it were unstable previously. If nothing will hang/crash, then I will be more than happy.

https://github.com/llvm/llvm-project/pull/84166