Implement building selection UI component

[rozniak]

This one might take a bit of thought... Junkbot and Junkbot Undercover have levels split into blocks of 15, arranged into 'buildings' or 'areas' on the menu.

There needs to be a UI component for this, but it's not super straight forward because the layout is very different between the two games.

Here's the building selection on Junkbot:

And here's the building (or I guess 'area') selection on Junkbot Undercover:

(It's probably obvious, but the gap in the 3D border in Undercover is similar to the look of the currently selected tab in the original Junkbot, if you get what I mean)

For now I suppose we could just have a simplistic UxComponent for either one, and think about extensibility when the time comes regarding custom levels/level packs.