This patch adds a new parameter ``--reason`` to ``openstack server lock``
command and ``--locked``, ``unlocked`` filtering parameters to
``openstack server list`` command. This can help users to provide a
reason when locking the server and to filter instances based on their
locked value from 2.73 microversion.
Implements blueprint add-locked-reason
Depends-On: https://review.opendev.org/#/c/661785/
Change-Id: Ib2714f98b24d47e570da8a6c231e765acd2ff595