Add `taco_view` and notebook showing TACO structures

[eriknw]

Also, update the strawman document with comments from our meeting.

We can now draw diagrams showing TACO-like structures: https://nbviewer.org/github/eriknw/binsparse-specification/blob/spz/spz_python/notebooks/Example_Rank4-taco.ipynb

I think this Python package may actually be useful (although extremely niche). I'd like to publish and share it. I don't like the name spz for it. Questions:

• Any suggestions for a new name? sparsetensor?
• Should I move it to a new repo so it doesn't clutter this one?

[BenBrock]

Maybe tensor_visualizer, tensor_format_visualizer, or sparse_format_visualizer?

[eriknw]

Renamed to sparsetensorviz.