qdev-monitor: include QOM properties in -device FOO, help output

Update -device FOO,help to include QOM properties in addition to qdev
properties.  Devices are gradually adding more QOM properties that are
not reflected as qdev properties.

It is important to report all device properties since management tools
like libvirt use this information (and device-list-properties QMP) to
detect the presence of QEMU features.

This patch reuses the device-list-properties QMP machinery to avoid code
duplication.

Reported-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Cole Robinson <crobinso@redhat.com>