Configure multiple auto-upload folders simultaneously

### Is your feature request related to a problem? Please describe.
I've a lot of folders which nextcloud-android sync's to my Server. But after getting an new mobile-phone i have to configure them an my new phone manually. It would be nice to have an Global-configuration for the "file-exists" Setting and an setting to select all local folders to synchronize with the Server with just one click.

### Describe the solution you'd like
Add an "Select all" button on the "Settings->Auto-Upload->folders" page
Add an Global / Default policy for the upload behavior.

### Describe alternatives you've considered
do it manually by hand :)

### Additional context
you are doing an great Job! Thank you so much!