Expose scheduler funtionality

[Readonly12]

Problem: Backup missed, because external Drive Destination is not connected. Backup should be started as soon as the drive is mounted.

As mentioned in #1301, there doesn‘t seem to be a cross platform way to check for mounted media.

So instead I‘m proposing to expose the Scheduler funtionality to be used in scripts. A simple commandline argument returning true/false if a backup is needed.

That would be enough to implement a backup on mount.

[m3nu]

You can already start a backup from a script:

--create PROFILE Create a backup in the background using the given profile. Vorta must already be running for this to work.

[Readonly12]

Thanks for the reply! I‘m sorry, but thats not the point of the issue. I already know about starting the backup. It‘s quite easy to start a backup on disk mount. The problem is that there is no way to check if a backup should be done, since the schedule functionality can‘t be accessed.