VMware: support spawn of stream-optimized image

This adds support of spawning instances using stream-optimized
disk images. This format is better suited as a glance format as it is
compressed, sparsed and optimized for streaming. The change uses the
oslo.vmware library to provide the functionality to transfer the image
to the server by importing it as a virtual machine.

Implements: blueprint vmware-vsan-support
Co-authored-by: Radoslav Gerganov <rgerganov@vmware.com>

Change-Id: I5c5c2aae733a2d55643d2ea5c293873b21325db6
Merge "VMware: support spawn of stream-optimized image"