home page cards for "explore example analyses": use static images for each app (as in legacy mbiome home page "explore viz tools")

[aurreco-uga]

requested by Dan on slack for microbiome July 25 2022.
I assume on Clinepi using the passthrough app we could default to the current analysis icon..

[dmfalke]

I think we should make this an integrated part of an analysis. I'm not sure how we can do it, yet.

One way could be to allow the owner of an analysis to choose a representative visualization whose thumbnail can be used for the cards (and possibly in other scenarios where we list public analyses).

If this is too opinionated, then we might just need to something more specific to Dan's preferences, such as making an associated thumbnail a "hidden" option, and that the thumbnail should be made manually.

[asizemore]

One way could be to allow the owner of an analysis to choose a representative visualization whose thumbnail can be used for the cards (and possibly in other scenarios where we list public analyses).

This would be great. We already generate all those thumbnail pictures so seems reasonable to keep using them!
@dpbisme what do you think?

[danicahelb]

also, keep in mind that the homepage will be redesigned in the (near?) future and the cards are likely to go away...