Enable wireless raw HID for the Keychron K8 HE

[shayangohar]

Description

Enable WIRELESS_RAW_ENABLE for the Keychron K8 HE so its 2.4 GHz wireless transport can forward raw HID battery requests through the common Keychron firmware handler.

This applies to the ANSI, ISO, and JIS K8 HE targets through the shared keyboard rules.

This is the keyboard-specific follow-up to #504. It doesn't affect keymaps, layouts, receiver firmware, battery calculation, or Bluetooth behavior.

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

Depends on #504, which provides the common wireless raw HID implementation.

Verification

• git diff --check passes.
• ANSI, ISO, and JIS K8 HE firmware targets build successfully from QMK MSYS
• The combined core and K8 HE changes were tested on a Keychron K8 HE using the Keychron 2.4 GHz receiver.
• A tray utility successfully retrieved a valid battery percentage over 2.4 GHz.
• Keyboard continues to function normally over wired connection, 2.4 GHz, and Bluetooth

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).