Real-time plots initial library

[blairlyons]

• [x] https://github.com/simularium/simularium-planning/issues/68
• [x] https://github.com/simularium/simulariumio/issues/122

Use case

As a user viewing a trajectory, I want to adjust metrics on existing plots and add plots of new metrics in real-time using UI.

Acceptance Criteria

• A developer can send spatial data to and request metrics from a Python server
• UI + Interaction design ready for implementation

Details

The initial library will only have a few functions, but it will be extensible.