tests/qtest: add various qtest_qmp_assert_success() variants

Add several counterparts of qtest_qmp_assert_success() that can

 * Use va_list instead of ...
 * Accept a list of FDs to send
 * Return the response data

Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230601161347.1803440-2-berrange@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
2 files changed