Create 2D histogram with JAX

[redeboer]

In order to create 2D histograms interactive in #31, you need to create the 2D histograms with JAX (or NumPy) instead of with Matplotlib, because that is faster on slider changes. This means replacing the call to matplotlib.pyplot.hist2d() with:

• a jax.numpy.histogram2d() can computes the bin values
• drawing of the computed bin values with pcolormesh().

There are no examples yet of how to do this on compwa.github.io/reports, but you can have a look at this answer on StackOverflow.