[qtcontacts-sqlite] Report added contacts IDs via storeSyncContacts

Added contact IDs are typically necessary for the caller to store.
[qtcontacts-sqlite] Ignore non-data values when comparing sync details

Values such as provenance are not relevant when comparing contact
details from different origins.
[qtcontacts-sqlite] Do not use OriginMetadata for sync contact identification

This is no longer necessary since the exported ID is preserved if
an incidental sync-target contact is added to a previously exported
local contact.
Fix comment to describe current situation