Add keycode aliases for Japanese JIS kana input (#24921)

[stringthread]

Description

Defined the keycode aliases based on the Japanese JIS kana input (かな入力), whose keymap is shown below:

Kana keymap without Shift

Kana keymap with Shift

Here are the examples of the keycode aliases. They starts with JK_.

Letter	Alias	Keycode
あ (a)	JK_A	KC_3
か (ka)	JK_KA	KC_T
゛(voiced consonant mark)	JK_VOICE	KC_LBRC

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

• Fixes [Feature Request] New extra-keycodes for Japanese JIS-kana-input #24921

Checklist

I'm not sure if documentation changes of tests are required.

• 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).