[clang] [clang-tools-extra] [clang-tidy] Add `bugprone-unchecked-expected-access` check (PR #233219)

[Valentyn Yukhymenko via cfe-commits]

BaLiKfromUA wrote:

### Note about the size of this PR:

I am planning to split this PR into [stacked pull requests](https://docs.github.com/en/pull-requests/how-tos/stacked-pull-requests), but I opened it as a draft for:
- visibility
- testing end-to-end
- high-level feedback from maintainers

https://github.com/llvm/llvm-project/pull/233219