WIP: postgres: create databases for all services

If a service is enabled, a database for it is created in postgres with a uniqque password. The service can then use this database for data storage instead of relying on sqlite.

roles/matrix-bridge-appservice-slack/templates/config.yaml.j2

@@ -10,5 +10,8 @@ homeserver:
     server_name: "{{ matrix_domain }}"
 
 dbdir: "/data"
+db:
+    engine: "postgres"
+    connectionString: "postgresql://matrix_appservice_slack:{{ matrix_addtional_databases | selectattr('name', 'equalto', 'matrix_appservice_slack') | map(attribute='pass') | first }}@{{ matrix_postgres_connection_hostname }}/matrix_appservice_slack"
 
 matrix_admin_room: "{{ matrix_appservice_slack_control_room_id }}"