Migrate website screenshot processing code to perennial

[arouinfar]

Discussion on design-website Slack channel:

@arouinfar:

Question about sim screenshots: It looks like the website automatically populates with the screenshots checked into master. This means that the pages for Greenhouse Effect and Energy Skate Park show screenshots for an upcoming version, not what’s actually published. Should we instead populate the screenshots from the latest published branch?

@mattpen :

Hmm, I think so. It will be a little tricky because we need code from the master branch of chipper to decide which versions of the screenshot to publish, but a checked out version of the sim. I think maybe we should migrate the screenshot processing code to perennial entirely. Just thinking out loud here, sorry. This isn’t a trivial change, can you please open an issue in perennial and assign me?

@kathy-phet:

Maybe this can leverage @jonathanolson's maintenance release code, which knows which is the published branch?

[mattpen]

This problem has popped up again and is being discussed in https://github.com/phetsims/website/issues/1322.

The chief reason we are pulling screenshots from master is because we have decided it is not desirable to conduct a maintenance release to release new images, because it triggers every app in the world to refetch the sim which has not changed. However, the majority of what has needed to change outside of the maintenance release cycle is actually the image sizes and configurations, and not the content. So we could feasibly use perennial master to determine target image configurations and use the sim's release branch for the image sources.

I don't think we need to leverage the maintenance release process for individual sim deploys, as the deployment knows which release branch it is releasing. But to migrate the task that deploys images for all sims we'd want to reuse that logic.