Merge libweston-desktop into main DSO

This MR mainly merges libweston-desktop into the core libweston DSO, so they can start sharing things more between them, and libweston can directly call through into libweston-desktop, etc.

Included with this are two random commits I had laying around - one to make kiosk-shell not link the desktop-shell protocols, and another to print the surface/view map status inside the scene-graph dump.