Epic #89595: Improve accessibility of backend
Add labels for creating a new page and following actions
As a blind editor, i need labels to creat a new page.
- there are no labels to orientate per screenreader
- (blind) editor does not know where to create a new page
- blind editor can find "create new page" via the pagetree (add label "create new page"), screenshot
- add a click handler for "add a new page", open the context menu
we test it on Typo V11.5.1 with a blind editor and Jaws(screenreader)