Implement EmulationStation Theme Compatibility

[acmeplus]

The goal of this ticket would be to implement partial EmulationStation Theme capability. By partial we mean that there's no need to implement tween animation, and other effects that are mostly driven by OpenGL acceleration.

As an initial set of goals, we could take es-epic-noir and make sure it can be read and used dynamically.

Here's a example link: https://github.com/c64-dev/es-theme-epicnoir