engine: GraphicsInfo in entities

This patch adds GraphicsInfo structure to VM and VmDynamic.

GraphicsInfo is a class that holds dynamic information about
GraphicsDevice (which contains static, non-runtime information only).

Change-Id: Ib11a8b63e76031f3137f2dfd0cd6551e9c19aca0
Signed-off-by: Frantisek Kobzik <fkobzik@redhat.com>
Bug-Url: https://bugzilla.redhat.com/1033547