The up_axis_update/forward_axis_update was the same logic between
the two, so factor that out.
Also use the same time reporting logic in PLY as in OBJ/USD/Alembic.
A new experimentatl STL importer, written in C++. Roughly 7-9x faster than the
Python based one.
Reviewed By: Aras Pranckevicius, Hans Goudey.
Differential Revision: https://developer.blender.org/D14941
