BUGFIX: document-node is redirected to the nearest parent on workspace change

[c4ll-m3-j4ck]

Previously, on changing from a workspace to another one that didn't contain the current document-node, an exception would be triggered if no new document-node could be found a single level up in the node-tree.

This PR changes this behaviour to walk up the node-tree until a document-node can be found (going up to the site-node eventually) and sets the new document node to the first shared one that can be found in the rootline.

[Sebobo]

Thx

[mhsdesign]

I could reproduce the bug

Wasn't able to locate any valid node in rootline of node /sites/neosdemo/features/navigation-elements/third-item/node-nh1g56sefvfkf/node-jwe1o0ggldihe@user-admin;language=en_US in the workspace live.

Scenario 1 is working currently:

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

But scenario 2 fails currently:

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

[mhsdesign]

I cant say if this covers or breaks every edgecase but both scenario 1 and 2 are now working correctly (im redirected to the closest page that exists in the base ws)