Add module input/output tensor PCA view

[spfrommer]

This would be a big new feature. For each element in the batch the user should supply a tooltip text and point color. There should then be a 2d view of the tensor in torchexplorer. For starters we could do a PCA-style thing and later something more sophisticated.

There should be a 2d scatter plot in the panel with each data point having an appropriate tooltip / color. Old points should fade out and there could also be a time slider.