[Keyboard] Fix up SplitKB keyboards

[drashna]

Description

This does a number of things:

• Moves the Kyria keyboard folder to /keyboards/splitkb/
• Updates the Kyria and modernizes the code (OLED/Encoder code in keyboard files for configurator compatibility)
• Adds VIA support to both the Kyria and the Zima
• Replaces the snprintf/sprintf function in user keymaps with char manipulation hack that saves a significant amount of firmware

Types of Changes

• Enhancement/optimization
• Keyboard (addition or update)
• Keymap/layout/userspace (addition or update)

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).

[cwebster2]

Changes lgtm.

[drashna]

@j-inc @winterNebs

A heads up, since this does alter your keymaps.

[marceloalcocer]

What was the reasoning behind this?

Defining LAYOUT_split_3x6_5 as LAYOUT breaks existing keymaps defined using LAYOUT_split_3x6_5 as four additional KC_NOs are required in the keymap.

If streamlining was the intention, would it not be better to remove LAYOUT_split_3x6_5 altogether?