feat: promote users to admin

This fixes: #298 (closed)

Summary by CodeRabbit

• New Features

  • Introduced a new endpoint for managing user permission groups within the Pleroma API, enhancing administrative capabilities.
  • Enhanced the TestApp class to support dynamic routing and introduced an administrative method for handling user events.

• Bug Fixes

  • Improved error handling in the DittoRoute class to streamline missing variable errors.

• Tests

  • Added tests for the new permission group management route to ensure proper access control and functionality.
  • Updated test cases for TestApp to streamline instantiation with routing.