Make it possible to use the JWT service with a local homeserver

I recently tried to use the dev configs with a local homeserver and found that the configuration was not compatible with this. We need to relax the network isolation and TLS cert verification requirements for fully local development to be possible.

backend-docker-compose.yml

@@ -7,12 +7,16 @@ services:
   auth-service:
     image: ghcr.io/element-hq/lk-jwt-service:latest-ci
     hostname: auth-server
-    ports:
-      - 8881:8080
+    # Use host network in case the configured homeserver runs on localhost
+    network_mode: host
     environment:
+      - LK_JWT_PORT=8881
       - LIVEKIT_URL=ws://localhost:7880
       - LIVEKIT_KEY=devkey
       - LIVEKIT_SECRET=secret
+      # If the configured homeserver runs on localhost, it'll probably be using
+      # a self-signed certificate
+      - LIVEKIT_INSECURE_SKIP_VERIFY_TLS=YES_I_KNOW_WHAT_I_AM_DOING
     deploy:
       restart_policy:
         condition: on-failure