[qtcontact-sqlite] Allow contacts to be deactivated

Deactivation allows a contact to be removed from the working set, yet
still retain its data and relationships.  If reactivated, the contact
should resume the state it had prior to deactivation.

A contact can be deactivated by saving a detail of type QContactDeactivated,
and reactivated by removing that detail.  A deactivated contact has
the IsDeactivated flag set in QContactStatusFlags.

By default, deactivated contacts are excluded from queries; they can
be explicitly included by matching for the IsDeactivated flag in
QContactStatusFlags.  Retrieving a deactivated contact is also possible
by specifying its contact ID directly.