Refactor modules into to folders and provide basic documentation for each module

[finnhartshorn]

Currently each module is just a single file with at times over 2000 lines in it. We need to refactor some of the larger modules into a folder with sub modules. We should also start to document each module and any key structs/methods.

The contributing.md should suggest reading the docs and joining the discord firstly and also contain some useful suggestion on how to structure things and link in with the rest of the codebase.