client: Do not try to send display_config until we've received the agent caps
client: Do not try to send display_config until we've received the agent caps

Currenty, we check the agent caps in RedClient::handle_agent_connected
for VD_AGENT_CAP_DISPLAY_CONFIG and if present send display_config, but at
this time we have not received the caps yet, so remove this.

Also the send_agent_display_config call in on_agent_announce_capabilities
lacks a check for _agent_disp_config_sent, and we send the display config
before announcing that we may do so by sending our own caps, which seems
inpolite.

freedesktop-unofficial-mirror/spice__spice,dezelin/spice,elmarco/spice,fgouget/spice,mathslinux/spice,elmarco/spice,SPICE/spice,virtualAMP/spiceplay,Fantu/spice,freedesktop-unofficial-mirror/spice__spice,freedesktop-unofficial-mirror/spice__spice,alon/spice-server,Fantu/spice,elmarco/spice,Fantu/spice,mathslinux/spice,alon/spice-server,elmarco/spice,virtualAMP/spiceplay,freedesktop-unofficial-mirror/spice__spice,fgouget/spice,Fantu/spice,dezelin/spice,mathslinux/spice,ya-mouse/spice,elmarco/spice,dezelin/spice,virtualAMP/spiceplay,alon/spice-server,SPICE/spice,fgouget/spice,dezelin/spice,dezelin/spice,ya-mouse/spice,alon/spice-server,alon/spice-server,fgouget/spice,SPICE/spice,mathslinux/spice,freedesktop-unofficial-mirror/spice__spice,ya-mouse/spice,virtualAMP/spiceplay,mathslinux/spice