Add the QOM unit tests to the QOM maintenance area so that maintainers
get CC'ed on changes and to document QOM test coverage.
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NIgor Mammedov <imammedo@redhat.com>
Signed-off-by: NAndreas Färber <afaerber@suse.de>