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/jellyfin/tasks/main.yml

@@ -12,7 +12,7 @@
     name: 'jellyfin'
     image: linuxserver/jellyfin
     networks:
-      - name: nginx-internal
+      - name: external
     volumes:
       - "{{ data_folder }}/jellyfin:/config"
       - "{{ media.tv }}:/data/tv"