SyncEngine: Fix renaming of folder when file are changed (#5195)

Two bugs:
 - The change filed are not considered as move, they are re-downloaded
   but the old file was not removed from the database. The change in
   owncloudpropagator.cpp takes care of removing the old entries.

 - Next sync would then remove the file in the server in the old folder
   This was not a problem until we start reusing the sync engine, and
   that the _renamedFolders map is not cleared. We were before deleting
   a non-existing file. But now we delete the actual file.

Also improve the tests to be able to do move on the server.
This include support for file id.

Issue #5192