Syncronization with self-hosted server #434

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

This wonderful app could become much more useful if we could synchronize local data on mobile to our private self-hosted servers with such services as Super-productivity's Supersync or any WabDAV provider (Nextcloud, Opencloud, Bewcloud, etc.)

Why do you want this feature?

The goal is not to use it on all devices but have a backup of your data on your own server and maybe sync mobile devices between them, migrate data easily.

Additional information

No response