Playground output result (formerly #704 and #420)

[tsnobip]

I just rebased on master @aspeddro work (#704, based on #420 work by @diogomqbm).

todo:

• make it work with JSX automatic (any idea why jsx-runtime is not defined in this case?)
• explain how to display something in the render output pane and display an error when the conditions are not met
• display console messages: I'll likely just rebind console log, info, warn, error so that they append messages to a list

[fhammerschmidt]

this got merged in #875 🎉