Expose a get_spice_console RPC API method

To mirror the existing get_vnc_console RPC API method, expose a
new get_spice_console RPC API method. The only console type
supported currently is 'spice-html5' which is equivalent to
'novnc'

Blueprint: libvirt-spice
Change-Id: Iab9d3dfc3564a122a8cd2b53d34fdcc725bfa29b
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Merge "Expose a get_spice_console RPC API method"