Add histograms of areaCell and dcEdge to init plots

[xylar]

Last 2 plots in:

Checklist

• [x] Document (in a comment titled Testing in this PR) any testing that was used to verify the changes

[xylar]

Testing

I ran the IcoswISC30 mesh and init tests on Chrysalis to produce the image above.

[xylar]

@golaz and @proteanplanet, are you okay with these or are there more tweaks you'd like to see?

[xylar]

The frequency is on a log scale for other plots, Perhaps that would make sense here, too. I'll try that.

[xylar]

Yeah, probably the version on a log scale makes a bit more sense for consistency and because there's a bit more info there.

[xylar]

I fixed the min/max values to be the original ones (m^2 and m, rather than km^2 and km) to hopefully avoid potential confusion.

[xylar]

Thanks @proteanplanet!