Allow setting a delay before auto upload / auto upload on-device deletion

### Actual behaviour
-Tell us what happens

Set auto upload to delete after upload. Take a photo. Go to show it to someone in the on-device gallery, and it's gone. Go to edit it on device, it's gone. Go to email/text it, it's gone.

### Expected behaviour
-Tell us what should happen

It's very convenient to have photos auto uploaded, and deleting them after successful upload helps manage device space utilization. But the immediacy of the upload/delete causes usage problems.

Ideally, should be able to set a delay between the photo being created and the upload/delete (i.e., file age greater than x minutes). Setting the delay to zero would work as it does now. Setting it to greater than zero would only consider photos/videos that we last modified per the setting.

### Steps to reproduce
1. Take a photo
2. Open the gallery
3. Where's the photo?

### Environment data
Android version: 8.0

Device model: OnePlus 5

Stock or customized system: Stock

Nextcloud app version: 3.0.3

Nextcloud server version: 13.0.0