[FEATURE] Godot Font System integration

[ashifolfi]

Currently freetype is used for the font engine, ideally we should be using the font system in Godot to allow for font resources to be shared with RmlUi and Godot's own Control nodes.

[ashifolfi]

I actually already started on this. if you notice the new build setup removes freetype and there's a base stub of a font engine interface.

That's also why it crashes on startup now. There's no font engine setup in RmlUi so it crashes trying to access it.