Refactor visualizers package to improve separation between package specific visualizers and reusable visualizers

[ncguilbeault]

Summary

This PR refactors the visualizers package to enhance modularity and maintainability. This update introduces a clear separation between package-specific visualizers (e.g. Bonsai.ML.Visualizers.LinearDynamicalSystems) and reusable visualizer utilities/base classes (contained within the core Bonsai.ML.Visualizers). This improves the user experience for those who only wish to use a single Bonsai.ML package with it's associated visualizers, and speeds up/lightens the installation process by not having to reference all Bonsai.ML packages within the core Bonsai.ML.Visualizers package.

[glopesdev]

Everything looks good in general, my main question is whether we will ever only have visualizers in these packages, or if we will have editors or other visual configuration controls as well.

In general we use the suffix .Design for similar packages, e.g. Bonsai.Vision.Design which include both visualizers and interactive editors. In this case the naming would be Bonsai.ML.LinearDynamicalSystems.Design and Bonsai.ML.HiddenMarkovModels.Design if we go for the same standard.

[glopesdev]

Just adding a few typos / minor suggestions, but otherwise LGTM. In the GitHub actions output (actions/runs/10740426883) there seems to be a few minor XML doc strings that maybe you could add, but otherwise I'm happy to merge this.