Accessible multiple choice

Makes the options in a multiple choice question tab navigable / answerable, as well as Also applies the same fix to multiple choice assessments (ie, collections of multiple choice questions) in a "tighter" layout.

Adds a global override for buttons in a hover state not to have a shadow because I'm tired of overriding them :).

Testing story

Tested on a standalone multiple choice level, as well as its appearance in a multiple choice assessment.