Automaticaly download on metered network option

### Is your feature request related to a problem? Please describe.
I have unlimited mobile data, and since my WLAN is... not the best, I usuually use Mobile data. This causes Auto-Upload to not work. It says "waiting for non-metered wifi". Thats annoing.

### Describe the solution you'd like
Most Apps (e.g. F-Droid) have an opt-out setting like "Download on unmetered network only". Its on by default, but if you want to download over mobile data, you can manually disable it. Nextcloud should have the same setting (for uploads and downloads, etc.)

### Describe alternatives you've considered
When manually tapping on an item in the "Failed" upload list, it gets in the queue and says "Waiting for non-metered wifi". If I manually tap it, it should upload. If i _manually_ trigger an automatic action, I want things to be done **now**.