By default
OVRSpatialAnchor will be spawned at user's hand's / controller's position. Disable FollowHand property to spawn the
OVRSpatialAnchor at the specified position and orientation. See SpatialAnchorCoreBuildingBlock
.OnAnchorCreateCompleted event to get notified when the anchor is created. See also Editor/BuildingBlocks/BlockData/SampleSpatialAnchorController in the
Meta XR Core SDK for an example of how to use this class.