The tag options are not implemented out of concern for diff size.
This splits the context menu classes out to a new "iconized" style which is common across a number of context menus, including the UserMenu.
Some of the badge/sublist styles had to change to better accommodate the menu icon lining up.
This also contains the framework required for https://github.com/vector-im/riot-web/issues/13961
0755b4c148
