Make input schemes game specific, not scene specific

[twaritwaikar]

We will have LOTS of duplication of effort as well as input binding data if we do store input keybindings per scene. We should store them per app i.e. like we do in the editor, and let us choose which input bindings the level needs at runtime

[twaritwaikar]

Actually having per-scene input bindings may not be that bad of an idea because we will potentially have a lot of different input configurations in the entire game with a lot of per-scene customization.

It may be feasible to have both kinds of input bindings in the engine. Both in the game and the scene and in case of name collisions, scene binding should be selected.