Possibility to stop synchronisation of a file or a folder

### Is your feature request related to a problem? Please describe.
I synchronised a file. but I'dd like to stop this synchronisation. On the menu I can just update the synchronisation, but I can't stop the synchronisation.

### Describe the solution you'd like
When a file or a folder is synchronised, in the menu detail add the possibility to "keep just on cloud"

### Context
Version of Nextcloud application for android : 3.28.1

Best regards
Oliu