TASK: Evaluate and remove "am-ui-" items

In 8.2, some functions (split, lock, pin, move) that previously were associated only with moderation can now be associated with non-moderator user roles. As such, /active/am-ui.css, which supports a couple of UI elements (like move), is now loaded for all users. Along with the CSS file (of which it looks like only one class is still used), there are some other inherited items in the /active/ folder that should be evaluated and either removed (16-bit sprites) or merged/replaced.