Incremental release providing workarounds for changes in related APIs.

1. Explicitly ignore OpenXR SessionSubsystem. The OpenXR session is not reporting the correct tracking state, but instead always reports TrackingState.None. This causes WLT to incorrectly believe tracking is lost. Ignoring session's tracking state until it is fully implemented.

2. Conditionally adopt new AR Foundation signature for creating and destroying anchors. Old (deprecated) signature was arAnchorManager.AddAnchor(pose), the new is gameObject.AddComponent().

3. Avoid race condition when trying to use ASA SpatialAnchorManager.CreateSessionAsync() before the SpatialAnchorManager.Start() is called.