GTG_Groups

Features
- Predefined Group Flags:
  - Added keepPublic, keepPrivate, and keepAsCreated flags for predefined groups in the editor.
    - Groups with keepPublic/keepPrivate cannot toggle privacy settings.
    - keepAsCreated restricts changes to group attributes (WIP).

- Enhancements
  - Group Management:
    - Empty predefined groups are not forced to be public anymore.
    - Group list is now sorted by radio frequency.
    - Join Group Button Behavior: Adjusted to disable/enable based on request status and group join permissions.
  - Gamemaster Privileges:
    - GMs can bypass locked groups and join them without a request.
    - GMs can promote themselves to group leaders.
  - Group Creation:
    - Player may create new groups if empty ones (likely predefined ones) are present
  - Private Group Behavior:
    - Groups with the keepLocked flag stay locked even if empty.