Improve networks

Create a single external network called "external".
Create container-specific networks.
Only a few containers need access to these.
So far: openldap, postgres.

roles/keycloak/tasks/main.yml

@@ -5,8 +5,9 @@
     ports:
       - "8080:8080"
     networks:
+      - name: external
       - name: postgres
-      - name: nginx-internal
+      - name: openldap
     env:
       "KEYCLOAK_USER": "{{ vault_keycloak_user }}"
       "KEYCLOAK_PASSWORD": "{{ vault_keycloak_password }}"