vairdraw-src

A json config 'interaction-set:hand-tracking:hand-models' is used
to define the 3D models to use for the left and right hands, if
'interaction-set:hand-tracking:enbale' is set to true.

The ApplicationBase calls the hardwareset to create the hand models.
Only implemented in the OpenXR hardwareset.

TODO: check that hand-tracking is available in the OpenXR runtime to
avoid loading useless hand models.