Customize: Allow menu creation in locations pane

Adds a link to the menu creation workflow from the locations selector in the nav menu control.

Props bpayton, westonruter, Travel_girl, melchoyce, celloexpressions.
Fixes #36279.

Built from https://develop.svn.wordpress.org/trunk@41899


git-svn-id: https://core.svn.wordpress.org/trunk@41733 1a063a9b-81f0-0310-95a4-ce76da25c4cd