Allow forcing a build in artifacts workflow dispatch

Sometimes it is useful to bypass the revision check when we need to make
changes to the runtime_commit_artifacts script. The `force` input can be
passed via the GitHub UI for manual runs of the workflow.

ghstack-source-id: cf9e32c01a565d86980277115f41e3e116adf376
Pull Request resolved: https://github.com/facebook/react/pull/31027