Allow to dismiss all (grouped) "Upload failed" notifications

### Is your feature request related to a problem? Please describe.
When many files fail to upload (either because of connection problems, or of power management), the notification drawer becomes filled with countless upload failed notifications. These are only dismissable one-by-one, instead of being able to dismiss the full group of notifications.

### Describe the solution you'd like
I don't know much about the inner workings of android notifications, but is there a way to change the notification type or whatever, so that the notifications can be dismissed as the whole group that android groups them as?

### Describe alternatives you've considered
I've considered disabling the notification altogether via the android notification settings, but I don't like that, as I would miss if anything important fails to upload.