[clang-tools-extra] [clang-tidy] Move part of bugprone-unhandled-code-paths to a new check readability-trivial-switch (PR #198237)

[Zeyi Xu via cfe-commits]

https://github.com/zeyi2 approved this pull request.

Code and tests LGTM, but please wait for other reviewers :)

https://github.com/llvm/llvm-project/pull/198237