Use the same type for WebCodec and WebRTC AV1 runtime flags
<rdar://problem/104066726>
Pull request: https://github.com/WebKit/WebKit/pull/8444
Committed 258720@main (dd46e21f601b): <https://commits.webkit.org/258720@main> Reviewed commits have been landed. Closing PR #8444 and removing active labels.