Feature request: Collapsible UI elements

[dhicks]

tl,dr: UI elements like tracks, track collections, and assets should be collapsible, so that they take up less UI space when not needed

Consider the legacy tracks. These take up a significant chunk of screen space for me — roughly the height of the visible part of the Tracks tab — and are right at the top of the Tracks tab. So 90% of the times I go to the Tracks tab, I need to scroll down to the track collection that I actually need. Similarly, the Campaign Combat Tracks collection will usually be empty, but still takes up about 25% of the visible height. If these collections could be collapsed to show just the header, they'd take up maybe 10% of the visible height each.

Assets also take up a big chunk of UI space — I can just barely view 2 asset cards side-by-side — that usually isn't necessary.

By the way, excited that the new version was released! I'll probably some time today re-organizing all my homebrew.