♻️(frontend) derive is_administrable from participant metadata

The is_administrable flag was previously read from the room API
response through the room serializer, giving the frontend static
information about the user's rights.

Refactor the frontend so it derives this flag from the participant
role carried in the participant metadata instead.

Two benefits:

* The flag now updates live along with the participant
  attributes/metadata, so role changes are reflected immediately.
* It removes the duplication between the API response and the
  metadata, which both used to determine the user's capabilities.

src/frontend/src/features/rooms/livekit/hooks/useIsAdminOrOwner.ts

@@ -1,6 +1,17 @@
-import { useRoomData } from './useRoomData'
+import {
+  useParticipantAttribute,
+  useRoomContext,
+} from '@livekit/components-react'
+import { ParticipantRole } from '@/features/rooms/api/ApiRoom'
 
 export const useIsAdminOrOwner = () => {
-  const apiRoomData = useRoomData()
-  return apiRoomData?.is_administrable
+  const room = useRoomContext()
+  const localParticipant = room.localParticipant
+  const role = useParticipantAttribute('room_role', {
+    participant: localParticipant,
+  })
+  return (
+    role !== undefined &&
+    ['administrator', 'owner'].includes(role as ParticipantRole)
+  )
 }