[QP] Color inversion control functions.

[elpekenin]

Description

This has two main goals:

• Easier configuration for end users, when their hw doesnt work with the default init sequence:
  Instead of overriding it (__weak__ function) with the command flipped... Just call these functions.
• If user has several of the same device (lets say st7789) needing different inversion values, it is now easier to do (no need to use qp_comms.h functions from user code)

To avoid code duplication (eg all ili9xxx use the same pair of commands), i've added files for family-specific logic. As a bonus, since that needed to check "is this family of devices enabled?", mk logic was partly rewritten, reducing duplication.

As discussed on Discord, even tho this "bloats" the amount of functions, it is (for now?) preferred over adding it to the standarized API because some devices wouldnt be able to support it.

Extra: Took the chance to remove != NULL checks from docs, since #20481 added those to the core code and users dont need them anymore.

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: C, Python
• 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.
• 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).

[elpekenin]

Dunno why i didn't open in draft... This is yet to be tested.