New searchbox component

[rsek]

Search/filter box component that should make things a bit DRYer on the movesheet. Will hopefully plug into the asset browser, too.

• make sure it works with the search event
• determine whether this is best managed via emit, injection, or some combination of the two
• review + revise CSS styling
• optional: implement on e.g. the asset browser?
• fix border radius bug on move filter results