Move containers storage to /var

[PlqnK]

Manual intervention required before updating

Change the way to store containers data.

Data is now stored in /var/containers instead of /opt/containers.

There's now 3 main directories to store containers data:

• config
  • User generated text configuration files.
• data
  • Services automatically generated data, like configuration done through their webui.
• runtime
  • Services runtime data like database runtime directories, cache folders etc.

The current file tree is as follow:

/var/containers/config
  openvpn-client
  traefik
  ttrss
/var/containers/data
  traefik
  transmission
  sabnzbd
  prowlarr
  radarr
  sonarr
  bazarr
  lidarr
  readarr
  mylar
  overseerr
  plex
  tautulli
  calibre
  calibre-web
  komga
  nextcloud_mariadb
  nextcloud
  photoprism_mariadb
  photoprism
  ttrss_postgres
  ttrss_app
/var/containers/runtime
  nextcloud_mariadb
  nextcloud_redis
  photoprism_mariadb
  photoprism/sidecar
  photoprism/cache
  ttrss_postgres

In order to migrate you need to copy the current containers data directories content to the new file tree, using cp or rsync. Analyze the diff of this PR to see the source and destination directories for each volumes.