Forward availability notification from WebInspector daemon from the UI process to the WebContent processes.
<rdar://problem/126946795>
Pull request: https://github.com/WebKit/WebKit/pull/28016
Committed 278235@main (362c47aa678d): <https://commits.webkit.org/278235@main> Reviewed commits have been landed. Closing PR #28016 and removing active labels.