9.0 Ensure that document-node is redirected to the nearest parent on workspace change

[mhsdesign]

The pr #3734 fixed the behaviour in Neos 8.3 but the code was not upmergeable.

The current 9.0 implementation throws many phpstan errors and is probably doomed in some way and must be refactored.

neos-ui/Classes/Controller/BackendServiceController.php

Lines 476 to 480 in 7169667

	// If current document node doesn't exist in the base workspace,
	// traverse its parents to find the one that exists
	// todo ensure that https://github.com/neos/neos-ui/pull/3734 doesnt need to be refixed in Neos 9.0
	$redirectNode = $documentNode;
	while (true) {

Both scenariao should pass at the end.

Scenario 1:

create workspace
create new subpage in workspace and publish and highlight it
change workspace to live again

Scenario 2:

create workspace
create new subpage in workspace
create new subsubpage in workspace
publish and highlight the new subsubpage
change workspace to live again