Add automatted tests for Nav block editable list view (#49433)

* Scaffold initial test

* Assert on menu structure

* Refine structure test filters

* Assert using appender to add menu items

* Improve assertions to check the type of the link being inserted

* Improve asserting on Page and Custom links being 1st and 2nd results

* Test block removal

* Make test describe blocks consistent with other tests

* Add test for editing items

* Test for adding submenus

* Remove uneccessary test wording

* Remove unecessary click on List View tab

Should be visible by default. Left one test which will fail if the tab isn’t automatically pre-selected.

* Extract blocks to a var

* Add Link Control test helper and extract relevant portions of tests

* Extract util for getting result text

* Remove unneeded focus of item to trigger options menu

* Avoid overly complex selectors by targetted Submenu for item removal test

* Remove comment

* Test editing a menu item actually updates in the list view

* Remove .only