[UptestTestChecks][NFC] Share some common command line options code
Summary:
Add a function common.parse_commandline_args() that adds options common
to all tools (--verbose and --update-only) and returns the parsed
commandline arguments. I plan to use the shared parsing of --verbose in a
follow-up commit to remove most of the `if args.verbose:` checks in the
scripts.
Reviewers: xbolva00, MaskRay
Reviewed By: MaskRay
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70428