Dashboard UX: implement measures & dimension visibility menus

[hamilton]

The metrics explorer will need to implement menus that enable the user to change the visibility. A fast-path here would be to use the existing menu components insrc/lib/components/menu and look at examples of the menus in action.

These menus can be implement in a dev route, or done directly in the existing dev route for the metrics explorer (shoudl be called dev/leaderboard or dev/explore as of this issue filing).

Some features:

• it should be a button that creates a floating menu component
• it should create a list of menu items that either have a checkbox or don't have a checkbox. If there is no checkbox icon, work with marissa to get one in figma and add it to the repository.
• optionally, it would be nice if we had quick fuzzy text searching of the menu items. If this is infeasible, it's better to land the code without it, but please file a follow-on issue for that.

[hamilton]

I think that either @djbarnwal or @ericpgreen2 could take this on once the layout has been cleaned up.