Handle Drive edition of a document already under a sync root

This use case is buggy, typically :

• Edit a document => synchronizes it under Locally Edited
• Register its parent folder ('Test WS') as a sync root => 'Test WS' is synchronized with the file inside it
• Edit the document from the Locally Edited folder on the file system
  => it is well updated server-side, but locally it is removed from Locally Edited and created inside 'Test WS' with the deduplication suffix __1

Note that at last step if we edit the file locally from 'Test WS' there is no problem.

Other scenario:

• Edit a document from a synchronized folder
• Update its content from the server
  => Content is updated under the Locally Edited folder but not under 'Test WS'

We should probably handle all doc pairs with the FileSystemItem id sent by the server in the remote changes instead of the first one only.
See Synchronizer._update_remote_states:

doc_pair = session.query(LastKnownState).filter_by(
                local_folder=server_binding.local_folder,
                remote_ref=remote_ref).first()

=> use .all() instead of first()?