Make GAME_DIMENSIONS less hardcoded

[Square789]

This would require throwing references to the game all over the place and then notifying everything having this reference if the game dimensions ever were to actually change or designing the systems using the dimensions to use the reference all the time.

This is not too necessary for now as FNF is relatively hardcoded to always be 1280x720, but for stuff in core like cameras it may be cleaner.