Workflow: Transformation module for digesting data and setting XformOps on Prims.

[Sasbom]

#30 (comment)

@BigRoy brought up a point that the camera translation function from could be generalized.
I think it'd be a good idea to extend this to rotation and scaling and the transformation matrix operations too,

This would be convenient when building out #26 .

and would also offer generic versions of some functions in the render_util module,
which would be particularly useful in #30 .

I propose that we keep other attributes in mind and structure it like so

usd-qtpy
|
| - lib
|    | - attributes
|        | - __init__.py
|        | - transformations.py
|        | - primvar.py
|        | - metadata.py
|
| - render_util...

On a small sidenode:
We could put render_util in lib too. I don't exactly know what belongs there and what doesn't.

That's all for now, folks