Update spec to support spice and rdp console type

Implement console_urls attribute of OS::Nova::Server that would lazily
resolve the URL of specific console type based on key provided.

Specifies blueprint vnc-console-attr

Change-Id: I896fede7a57dbeb4633ab79c9189c1e360dcb600
Co-Authored-By: Pavlo Shchelokovskyy <pshchelokovskyy@mirantis.com>