Improve social media previews of refine.bio

[arielsvn]

With #844 we'll be able to provide custom descriptions in the meta section for all pages. We could also add an image.

We should prioritize this for twitter, but we can also add it to other networks.

[arielsvn]

I wonder if we could generate an image like the one in AlexsLemonade/refinebio#1832 and attach it to experiment pages when they are shared.

[arielsvn]

Talked with @kurtwheeler, we could also generate a single image that we use for the whole site. One idea was a heatmap of the human compendia, with refinebio's logo somewhere.