[Feature Request] Nextcloud Syncronisation Support

[voxelized-voxel]

Currently, only Google Drive and Dropbox are supported for synchronizing your configuration. There are concerns regarding the usage of both providers, with some users preferring to avoid them. I propose adding support for a third, more open and privacy-friendly provider called Nextcloud. You can find more information about it here:

https://nextcloud.com/
https://github.com/nextcloud

It has all the features needed to be supported by uBlacklist.