[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