Build an a JS Test environment as an artifact in CI

[paddymul]

There is a test application that exercises bucakroo, found via npm run dev. This shows how buckaroo renders as a front end only component, not depending on the notebook. Sometimes it is nice to build functionality into the frontend that the backend isn't yet generating outputs for. Separating the two dev processes can encourage more contribution from differently skilled people.

Insert a screenshot of the JS Dev environment.

[paddymul]