fix for 1887 : Define new interfaces used by the synchronization provider so that LocalBackend operations are not exposed
These changes modify the SynchronizationProvider API so that the LocalBackendXXXOperation
are not exposed by this api anymore.
The solution is to use the PreOperationxxxOperation and PostOperationXXXOperation :
the PreOperation methods now use the PreOperationXXXOperation interface
the PostOperation methods now use the PostOperationXXXOperation interface
the handlConflict methods now use the PreOperationXXXOperation interface