* Removes server rendered vector-tab-noicon class from legacy Vector as it is
not currently used.
* Adds menuTabs.js responsible for adding the vector-tab-noicon class when menu
items are added to tabbed menus. This is only used in vector-22.
* Adds unit test
Bug: T320691
Change-Id: Iffad86125f8754305f592ddc19d894866bd6dedc