[FEA] Multigpu demo

[lmeyerov]

Is your feature request related to a problem? Please describe.

Unclear how to do gpu / multi-gpu well, such as on logs -> graph

• single gpu
• multi-gpu
• parallel io

Describe the solution you'd like

Using a challenge dataset:

• bootstrap
• progressively powerful views for each of the above
• an interactive control for it
• tutorial

Describe alternatives you've considered

Additional context

Part of GTC 2021 talk & graphistry/pygraphistry#221