Add a stand-alone run-tests script to webkitbugspy that runs webkitbugspy tests without relying on webkitpy's harness.
<rdar://problem/111704754>
Pull request: https://github.com/WebKit/WebKit/pull/15512
Committed 265849@main (d60ad3ede16d): <https://commits.webkit.org/265849@main> Reviewed commits have been landed. Closing PR #15512 and removing active labels.