ostream is included through a reference to allow for directly referencing XrSceneUnderstanding.h
Functions based on xr::ExtensionContext are updated to only require the xr::ExtensionDispatchTable. None of the xr::ExtensionContext specific functionality is used in this header. Basing functions off xr::ExtensionDispatchTable allows objects inheriting from xr::ExtensionDispatchTable to be used.
Helper functions were added for obtaining scene planes
This review has the following changes: