Restart XR immersive session foreground activity if needed when process is unsuspended
<rdar://problem/107913685>
Pull request: https://github.com/WebKit/WebKit/pull/16725
Committed 267097@main (ce151b92a063): <https://commits.webkit.org/267097@main> Reviewed commits have been landed. Closing PR #16725 and removing active labels.