Allow backup sets to be unscheduled

[stewartadam]

Backup sets currently automatically create a crontab entry unless they are disabled, at which point the GUI will refuse to backup the set (even if manually triggered).

This behavior can be overridden using fwbackups-run -f on the CLI but there is no GUI equivalent functionality.

Adjusting GUI behavior to permit backups of disabled sets when clicking Backup Set Now would enable the scenario for users to configuring a backup that they wish to run repeatedly but trigger manually.

[stewartadam]

This didn't make the cut for 1.43.8-rc1 but will be added to the 1.43.8 final release.

[stewartadam]

Pushed a fix out, this will be in rc3. (edit: doesn't appear to be fully working when Enabled = 0)