add GOP, NONE and VIRTIO grapics models

This change extends the COMPUTE_GRAPHICS
module with 3 new traits for the GOP, NONE and
VIRTIO models.

Depends-On: https://review.opendev.org/#/c/647733/
Change-Id: I17945e8ad6ea5349f46c26e427a0f539ca5eba8b
Task: 30526
Story: 2005447

os_traits/compute/graphics.py

@@ -17,8 +17,11 @@
     # image metadata property
     # https://github.com/openstack/nova/blob/1f74441/nova/objects/fields.py#L501-L509
     'MODEL_CIRRUS',
+    'MODEL_GOP',
+    'MODEL_NONE',
     'MODEL_QXL',
     'MODEL_VGA',
+    'MODEL_VIRTIO',
     'MODEL_VMVGA',
     'MODEL_XEN',
 ]