docker: Activate graphql authentication when keycloak is available

It enables to test graphql authentication feature in the docker environment.

docker/conf/graphql-keycloak.yml

+storage:
+  cls: remote
+  url: http://swh-storage:5002
+
+search:
+  cls: remote
+  url: http://swh-search:5010/
+
+debug: yes
+
+introspection: yes
+
+max_query_cost:
+  anonymous: 500
+  user: 50000
+
+auth:
+  server: http://keycloak:8080/keycloak/auth/
+  realm: SoftwareHeritage
+  client: swh-web
+  cache:
+    # used to cache auth tokens
+    url: memcached://memcache:11211

docker/docker-compose.keycloak.yml

@@ -43,3 +43,10 @@ services:
     volumes:
       - "./conf/deposit-keycloak.yml:/deposit-keycloak.yml:ro"
 
+  swh-graphql:
+    depends_on:
+      - keycloak
+    environment:
+      SWH_CONFIG_FILENAME: /graphql-keycloak.yml
+    volumes:
+      - "./conf/graphql-keycloak.yml:/graphql-keycloak.yml:ro"