Syncoid - Better syncoid snapshot naming

[redmop]

Syncoid snapshots should have syncoid_source_destination type names. This will help with cleanup scripts when removing snapshots which have nothing to do with the host they are on. In other words, syncoid_hosta_hostb
syncoid_hosta_hostc

On hostb, hostc snapshots are not needed, and vice versa, so they can be deleted after X time. Maybe look to see if they exist on hosta, and delete them if they do not.

[redmop]

Make the cleanup and option in case it isn't needed

[redmop]

Note that there is a nas4free sync script that doesn't create snapshots when syncing, it just finds the latest that both ends have and syncs from there.

https://github.com/fritz-hh/scripts_NAS4Free