[REQUEST] Enable on-close & or on-demand External Tracker syncing

[cdloh]

Description It'd be great to be able to sync the current page / read count to external trackers on close & on demand. When this sync happens and it turns out the remote external tracker is further along then the current device it'd be good if you could choose which side of the tracker you want to resolve too and then sync against.

How would it improve the App? I personally largely read Compendium issues and the like. When moving between devices it would be really handy to have this feature so that I could sync the current page count rather then having to scroll around to find the right spot.

Additional context N/A