This adds support for the recommended CLI using the OpenStackClient,
without modifying the existing Blazar shell CLI.
The existing shell command classes are used, by introducing a check in
the base comand class to use either the client passed by Blazar shell,
or the client using the osc_lib client_manager.
The argument --physical-reservation is also removed for the create lease
command when using the OpenStack client.
Implements: blueprint openstackclient-support