[keyboard] add redragon/k715_pro

[temp4gh]

Description

Add support for new keyboard redragon/k715_pro.
Thanx!

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

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).

[temp4gh]

Hello Repository Owner/Collaborators,
This commit contained the wireless（Bluetooth） code.If there are any specific concerns, issues, or additional changes needed, please let me know. Your guidance would be greatly appreciated as I want to ensure my submission aligns with the QMK's standards and requirements.
Additionally, if there are any other steps I need to take or if there's an expected timeline for the review process, please feel free to share that information with me.
Many Thanx!

[stewartsoda]

This implementation appears to be incomplete. It is missing the MO(KC_RALT) functionality to read the battery level and display it on the number row LEDs and the functionality for the "Mac/Win" switch on the bottom of the KB.
Both of these exist in the stock firmware.
This is a good start, though.