contactmodel: use added information when adding conversation

After a sync, contactAdded will be emitted. But lrc was generating
a new conversation without the "added" information stored by the
daemon. Causing a smartlist with incorrect informations.

Change-Id: I5f05a905e831ec06353002fed40be403e3c753da
GitLab: https://git.jami.net/savoirfairelinux/ring-project/-/issues/1282