tests/qtest: add scenario for -readconfig handling

This test of -readconfig validates the last three regressions we
have fixed with -readconfig:

 * Interpretation of memory size units as MiB not bytes
 * Allow use of [spice]
 * Allow use of [object]

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220805115529.124544-2-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2 files changed