Blender Git Loki

XR: Fix crash/assert on loading controller model

When calculating controller model component transforms from glTF node
data, it was previously wrongly assumed that the glTF nodes would
always contain transform matrix values. However, nodes can instead
store their transforms as separate translation/rotation/scale values,
in which case the transform matrix needs to be explicitly calculated.
This was the case for the Reverb G2 controller models using the
Windows Mixed Reality runtime.

Special thanks to Werner Trunk for help with testing/debugging.