[clang] [UVT] add update-verify-tests.py (PR #97369)

[Nicolai Hähnle via cfe-commits]

https://github.com/nhaehnle commented:

This is a nice addition, but I think it should follow the conventions established by the existing update_*_test_checks.py scripts as much as possible, at least:

* Ability to parse RUN lines, re-execute them autonomously, and modify test files in place based on their output
* Proper argument parsing via the argparse library
* Name of the script itself

You should integrate with the UpdateTestChecks/common.py infrastructure as much as possible. At a minimum, the collection of test cases to update, the RUN line parsing, and stuff like `common.invoke_tool` should almost certainly be shared. This may require some minor updates to that common infrastructure, but that's a good thing.

The actual generating and updating of CHECK lines is probably sufficiently different that sharing might not make sense. That said, I wonder if this script can be generalized to automatically generate CHECK lines for other tools that produce diagnostic output.

https://github.com/llvm/llvm-project/pull/97369