Small round of rgb matrix optimizations

[XScorpion2]

Description

Small around of changes to the rgb matrix animation code hoisting a few more chunks of calculations out of the loops.

Types of Changes

• Core
• Bugfix
• New feature
• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)
• Documentation

Issues Fixed or Closed by This PR

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• I have tested the changes and verified that they work and don't break anything (as well as I can manage).

[mechmerlin]

I wish we had some unit tests to test these.

[drashna]

@mechmerlin I mean, there is Drashna CI, just need to kick it. :D

[XScorpion2]

I wanted to keep this pr small (unlike my other one) for this round. I'm thinking about the changes to make this giant file more modular / testable especially within the context of the animation functions themselves.

Current thinking is move each animation function into a separate code file, and update the function to take pointers to the necessary global values instead of accessing them via extern field. This way the function can be run directly with a set of test values and the results can then be validated without needing anything but just the animation code file itself.

[drashna]

Looks good to me, Works on both my planck light, and ergodox ez glow, without any issues

[yanfali]

Hoisting work out of loop bodies seems worthwhile. +1

[XScorpion2]

Latest version: #5304
Works with the test suite being developed for rgb matrix animations.