Allow disabling RGB_MATRIX_ANIMATIONS on system76 keyboards with a pre-procesor directive

[PeterFalken]

Description

Allow disabling RGB_MATRIX_ANIMATIONS on system76 keyboards by using a pre-procesor directive. Not defining the animations can free up storage space (~2.2KB or more on atmega32u4) to use on other features. When DISABLE_RGB_MATRIX_ANIMATIONS is not defined, the default behavior is unchanged - It's intended to be minimally invasive and straight forward.

This change can be activated on a custom keymap with the following code:

#define DISABLE_RGB_MATRIX_ANIMATIONS
#undef ENABLE_RGB_MATRIX_CYCLE_ALL
#undef ENABLE_RGB_MATRIX_CYCLE_LEFT_RIGHT
#undef ENABLE_RGB_MATRIX_CYCLE_UP_DOWN
...

An example of how it can be used on a keymap file can be found here.

Types of Changes

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

Issues Fixed or Closed by This PR

Checklist

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

[PeterFalken]

Thank you @leviport, for the feedback and testing - I really appreciate it. Updated the comment for the PR to reference 2.2KB, the extra space I noticed is probably associated with other features I had disabled on my configurations.