Add DK3000

[key10iq]

Description

This PR adds a replacement PCB powered by QMK for the Reuters DK3000 keyboard. The keyboard features Dome and Slider switches and a separate PCB with a controller. The PCB with the switch pads houses an 8-channel multiplexer, to which the matrix rows are connected, with another row directly connected to the controller. Therefore, a custom matrix was added to control this keyboard. The keyboard also has several indicator LEDs (some of which are connected in the Source setup, others in the Sink setup):

• 2 LEDs indicate layers;
• 3 LEDs indicate Caps/Num/Scroll Lock (for some reason, with the code for controlling the LEDs indicating layers, the lock indicator does not work when configured in the keyboard.json file);
• 1 LED (Alarm) is always on.

The top rows of the keyboard are used for macros, which are allocated the maximum amount of memory available.
The firmware is fully debugged and works perfectly.

Types of Changes

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

Issues Fixed or Closed by This PR

• Added new keyboard - keyten/dk3000

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).