Allow uploads to be scheduled separately from other file backups

Our uploads folder is very large. We don’t want to back it up on the same schedule as the rest of our files, because that would take up too many resources and too much file space. Currently, we don’t use UpdraftPlus to back up our uploads at all. The recent addition of incremental backups might make it feasible to resume using UpdraftPlus for uploads backups, but not if we have to back the uploads and all of the other files on the same schedule.