Update Docs: Split up z64.h

originally https://github.com/HarbourMasters/Shipwright/pull/3283

> This will be quite a large one and I will split this up into smaller PRs once complete but seems much easier to keep a centralised doc since there may be things that rely on each other somewhat.
>
> The process for this is to split up the structs, functions and variables found in z64.h, variables.h and functions.h based on their current state in decomp. All corresponding changes in naming will be updated and newly introduced macros/enums will be used.
>
> Later (in a separate PR) a second pass will be done to update the c files to remove magic numbers and cover other changes that were made in decomp when these splits were made.
>
> This will be my way of keeping track of the current progress of the include files:

* [ ] fault.h
* [ ] gfx.h
* [ ] gfxprint.h
* [ ] irqmgr.h
* [ ] jpeg.h
* [ ] mempak.h
* [ ] padmgr.h
* [ ] prerender.h
* [ ] quake.h
* [ ] rumble.h
* [ ] sched.h
* [ ] seqcmd.h
* [ ] speedmeter.h
* [ ] terminal.h
* [ ] tha.h
* [ ] thga.h
* [ ] z64animation_legacy.h
* [ ] z64curve.h
* [ ] z64game.h
* [ ] z64message.h
* [ ] z64ocarina.h
* [ ] z64pause.h
* [ ] z64skybox.h
* [ ] z64sram.h
* [ ] z64transition_instances.h
* [ ] z64view.h
* [ ] z64vis.h
* [ ] z64elf_message.h -> z64quest_hint_commands.h