Convert FdEnums to ScriptableObjects

[jukibom]

I get the feeling that using a custom enum implementation (FdEnum) was a bit much, and while there are some benefits there like the ability to populate dropdowns and perform lookups, it makes managing things like level data more painful than it should be. Adding new levels is fine but the ordering and working on which music is which etc is very much a painful task.

These could be better potentially with a LevelDatabase master SO which holds references to Level SOs and, potentially, some editor panel which allows changing the json metadata directly would be incredibly useful while still providing the dropdown population stuff from the SO or a base class (re-organising the music recently was a bit of a wakeup call!)