CLI sorting guidelines are defined in the cross project specs
repository: [1]
This patch deprecates --sort_key and --sort_dir and adds support for
--sort in the 'cinder list' command with the following syntax:
cinder list --sort <key>[:<direction>]
The --sort parameter is comma-separated and is used to specify
one or more sort keys and directions.
Server-side work for sorting by multiple keys is handled in [2].
[1] https://github.com/openstack/openstack-specs/blob/master/specs/
cli-sorting-args.rst
[2] https://review.openstack.org/#/c/141915/
Implements: blueprint cinder-pagination
Change-Id: Ie8c2c62b8c129f647f85d66d5bcfe4c8f0f4eedb