🔧(compose) add a LiveKit server to the stack

Based on @mathisbarthere's PR on openfun/Magnify migration to LiveKit.
These configurations might need to be updated.

Please refer to the documentation: https://docs.livekit.io/home/self-hosting/local/

The 'livekit-server --dev' will start a LiveKit in development mode,
the instance will use the following API key/secret pair:

API Key: devkey
API secret: secret

By default LiveKit's signal server binds to `127.0.0.1:7880`, adding the
option `--bind 0.0.0.0 allow other devices on your network to access the
server.

docker-compose.yml

@@ -40,6 +40,7 @@ services:
         - mailcatcher
         - redis
         - nginx
+        - livekit
   
   celery-dev:
     user: ${DOCKER_USER:-1000}
@@ -72,6 +73,7 @@ services:
     depends_on:
       - postgresql
       - redis
+      - livekit
 
   celery:
     user: ${DOCKER_USER:-1000}
@@ -148,3 +150,11 @@ services:
       - "8080:8080"
     depends_on:
       - kc_postgresql
+
+  livekit:
+    image: livekit/livekit-server
+    entrypoint: /livekit-server --dev --bind 0.0.0.0
+    ports:
+      - "7880:7880"
+      - "7881:7881"
+      - "7882:7882/udp"