console.c unit is over-crowded. This code is specific to the handling of
the QMP screendump command, so move it in ui-qmp-cmds.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230830093843.3531473-4-marcandre.lureau@redhat.com>