Starting with QEMU-6.2 started accepting a JSON object as argument for
'-device' which will also become the only syntax considered stable by
qemu in the future.
Since libvirt was recently converted to generate the properties via JSON
to begin wit we can start using it on the commandline as well, by simply
enabling the QEMU_CAPS_DEVICE_JSON capability, which we do by probing
for the 'json-cli' feature flag of 'device_add'.
Normally a change which changes a commandline output should be happening
only after the impacted real-caps test files are forked in the version
preceding the change, but in this case it's not necessary as the logic
for generating the device properties stays identical and we just change
the output format (avoid conversion). Additionally we still have a lot
of tests validating the conversion to the old commandline options.
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
