Adds support for a node's ``deploy_step`` (read-only) field.
The deploy step indicates which step is being performed
during the deployment/provisioning of a node.
It is available starting with Bare Metal API version 1.44.
Depends-On: https://review.openstack.org/#/c/579968/
Change-Id: I93ac628bca0822a9a359926389543f7db7fb3e56
Story: #1753128
Task: #22925