As part of the Role binding api create the input and output serializers without pagination and setup initial query for groups only

Acceptance Criteria

  Valid Requests
  - Returns 200 with correct structure: last_modified, subject (id, name, description, user_count), roles, resource
  - Groups with multiple roles return all roles without duplicates
  - user_count is accurate

  Parameter Validation
  - Missing resource_id → 400
  - Missing resource_type → 400
  - Invalid UUID → 400
  - Non-existent resource → 200 empty

  HTTP Methods
  - GET allowed; POST/PUT/DELETE/PATCH → 405

  Auth
  - No token → 401
  - Invalid token → 401
  - No permission → 403

  - Resource with no bindings → 200 empty array

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