spice-streaming-agent: handle capability negotiation
This patch completes the initial skeleton for capability negotiation.
It populates the outgoing message (CapabilitiesOutMessage) with a bit array listing, for each known capability, if it is supported or not.
Likewise, it unpacks the capability message received from the server
(InCapabilitiesMessage) and calls the function
server_capabilities_received
with a vector containing the
capabilities supported by the server.
Edited by Kevin Pouget