- Adds html-before-portlet to Menu.mustache
- Removes UserMenu.mustache and type def
- Factors out getCreateAccountHTML and getLoginHTML for generating HTML used in Menu
- Scopes UserLink template data under "data-vector-user-links"
Follow up to: 298f945983
Bug: T284584
Change-Id: I91104eb7c4fd12756e770561666f4c9a64da57d6