More plots for layer errors

[SamFerracin]

This PR adds swarm plotters for LayerErrors.

Preview

[ihincks]

Here is some early feedback without having looked at code.

1. As always, we need to consider scalability of the plots so they don't crash/burn/look horrible for larger datasets. The bar plots might have some trouble, especially with x ticks, or possibly just looking like a jumble of very thin lines. We should consider plotting only a subset of data and raising a warning.
2. One scalable alternative/other idea to bar plots consider would be plots of CDFs
3. I'm on the fence about having separate functions for 1q and 2q weights.

But in general, nice work, and "the more the merrier" for visualization options.

[ihincks]

Also for the x labels, I think you can use some subset of simple html tags to do text formatting in plotly. For example, use the <sub> tag for subscripts.