Hypervisor stats do not reflect accurate VCPUs and PCPUs usage, so
to have a correct picture we need to use Placement API along with
hypervisors.
We add VCPUs and PCPUs usage diagrams and Resource Provider tab
to display correct stats.
Since there is no python client for the Placement API, and the
OpenStack SDK doesn't support the endpoints we need, we call the
endpoints directly.
Related-Bug: #1974470
Related-Bug: #1397917
Change-Id: If41cea0edeec8c95717229eb017e32898417a891