The TrackableType(s) that were hit.
The HitType will be a subset of the trackableTypeMask argument of XRRaycastSubsystem.Raycast. For example, if
XRRaycastSubsystem.Raycast is called with TrackableType equal to TrackableType.PlaneWithinPolygon | TrackableType.PlaneWithinInfinity,
but the raycast misses the BoundedPlane's boundary, HitType would just be TrackableType.PlaneWithinInfinity.