Demonstrate modifying a live simulation in Vivarium

[blairlyons]

• [x] https://github.com/simularium/vivarium-models/issues/19
• [x] https://github.com/simularium/simulariumio/issues/63
• [x] https://github.com/simularium/vivarium-models/issues/18
• [x] https://github.com/simularium/octopus/issues/7
• [ ] https://github.com/simularium/vivarium-models/issues/17

Use case

As a developer, I want to change a simulation from the Viewer while it's running live.

Acceptance Criteria

• A Simularium viewer client locally that is connected to a Vivarium simulation also running locally
• A developer can change an agent's position in the viewer
• A developer can change the simulation engine from the viewer
• Those changes are reflected in the state of the model and in the live visualization in the viewer

[blairlyons]

This is de-prioritized in favor of prototyping with BioSimulators API