Add bottom 'ornament' overlay to ranked play

[LiquidPL]

This commit adds an always present overlay to all ranked play screens, meant to indicate to the user that a ranked play session in currently in progress.

This has been largely inspired by the pre-shader argon healthbar code. It shouldn't have the same performance concerns, however, since the paths are only calculated once when loading the drawable (and eventually when it is resized, if ever).

RankedPlayScreen:

Gameplay:

Currently the drawable overlaps with some components, but it will be resolved in later pull requests.

[peppy]

I'd really like to add more animation to the path part of this, but it's a bit hard to orchestrate with the way it's structured atm.

[LiquidPL]

I'd probably have to pull out the SliderPath parts out to some place where they're defined once on load (probably should have done that in the first place), so that they can then be used to drive any interpolations that would animate the paths.

[peppy]

First pass looks okay