scripts: qmp-shell: refactor helpers Refactor the qmp-shell command line processing function into two components. This will be used to allow sub-expressions, which will assist us in adding transactional support to qmp-shell. Signed-off-by: John Snow <jsnow@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Tested-by: Kashyap Chamarthy <kchamart@redhat.com> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>