feat: histogram visibility configuration

[gselzer]

It would be nice to configure ndv programmatically to display histograms by default - from @marktsuchida: "It's a teaching thing - we want scientists to be looking at histograms".

This might be as simple as adding a show_histogram_default parameter to the ArrayViewerModel, however there is likely some intricacy here, since we might configure:

1. Whether histograms can be collapsed.
2. Whether certain histograms should be visible by default.

[tlambert03]

yeah I like it. I agree that adding to ArrayViewerModel like #139 is a natural fit.