Request: store previous sync points, allow restore

[AshleyYakeley]

When notes are accidentally deleted, and then those deletions are automatically synced, it can be difficult to restore them.

To mitigate this, I propose that the Joplin NextCloud server app store previous synchronisation points, and allow the user to restore to a previous point.

The server could store all previous versions, or to save space, automatically delete points that are older than some set period of time.