Add some proper unit testing

[Vectorrent]

There is functional Jest code that already works, in an extremely limited capacity. To begin, I think we should create tests for each model version - to ensure that no version "breaks" during the course of development.

We can focus on testing individual functions later, after adding some basic model tests.

Part of this is going to involve the addition of a maxSteps argument, such that we can test for maxSteps number of iterations, per model. Today, training is just infinite. I added a basic trainSteps argument, to handle this.

[Vectorrent]

I setup some extremely basic smoke testing for each model version:
https://github.com/0-5788719150923125/ode/blob/main/tests

This should be easy to extend.