Enable management of WebKit process as extensions by default.
<rdar://problem/119390422>
Pull request: https://github.com/WebKit/WebKit/pull/21544
Committed 271784@main (52700c609159): <https://commits.webkit.org/271784@main> Reviewed commits have been landed. Closing PR #21544 and removing active labels.
Re-opened since this is blocked by bug 266252