Split camera.c

[someone2639]

camera.c 11148 -> 3178 2441 lines

See README for details on file structure

TODO's for the PR:

• Decide on whether it's worth adding a file for camera shake and camera sound

[someone2639]

I believe this PR is ready for initial review. As always, the README has the intended file structure in case there are comments on that.

Things to consider:

• Many enums and structs are still in camera.h, due to being a bit involved to separate into their uses (it would pollute the PR's changed files too)
• The functions in Image 1 might warrant a new file, camera_sound.c
• The functions in Image 2 might warrant a new file, camera_shake.c, or integration into the existing camera_math.c
• I have put a function only used by the behind_mario mode in its respective file, but it might be worth placing it in camera_math.c instead.

Image 1:

Image 2: