Manage PR deploys ourselves

[ivirshup]

@grst suggests:

I think it could be solved by combining two workflows where the first runs on: pull_request and uploads an artifact and the second runs on: workflow_run

I think I like this more:

• More explicit about how build happens, easier for us to customize
• Can share the exact build and deploy script
• Safer(?)

But I'd probably just go with the netlify thing for now since it seems to be working, I should really finish up a poster, and I want previews working for the ecosystem listing PR

Originally posted by @ivirshup in #66 (comment)