Check for recently uploaded backups before upgrades

[jhenkens]

I saw in the comments an old reference to look at sensor.backup_state, so I checked it out. Provided by the Google Drive Backup addon, and I thought it was pretty valuable. I have the backup addon configured to backup daily with Google Drive uploads, and figured a "best case" scenario is actually to check the recency of the latest backup in Google Drive! The sensor only seems to expose the latest backup from the backup addon itself, from what I can tell, and doesn't specify what type of backup is performed, both of which are flaws I'd say, but this still provides some excellent value.

[edwardtfn]

My challenge here is the fact that this sensor is only available for Google Backup add on. I know the Samba backup also have a sensor like this (with a different name, etc.), but there's no universal solution for that. Maybe we can have an input of users to select which backup solution they want to monitor and we adapt the routine based on that...