Make all message structs internal to spice
Make all message structs internal to spice

We move all message structs from spice-protocol to spice as
we want to be able to change these as needed internally. The
on-network format is no longer defined by these structures anyway,
but rather by the spice protocol description.

freedesktop-unofficial-mirror/spice__spice-common,Fantu/spice-common,Fantu/spice-common,SPICE/spice-common,fgouget/spice-common,Fantu/spice-common,fgouget/spice-common,elmarco/spice-common,elmarco/spice-common,Fantu/spice-common,freedesktop-unofficial-mirror/spice__spice-common,freedesktop-unofficial-mirror/spice__spice-common,SPICE/spice-common,elmarco/spice-common,fgouget/spice-common,freedesktop-unofficial-mirror/spice__spice-common,fgouget/spice-common,elmarco/spice-common,SPICE/spice-common