LiveView 0.17-dev. Slots, JS.add_class, LiveApps

With Slots and JS Commands LiveView has almost everything now to be able to convert Bootstrap, Bulma or especially Tailwind UI into a really fantastic Phoenix/LiveView component library. Probably won't even require AlpineJS...

Although I think 'Declarative Assigns' from the roadmap (already in Surface UI) would make everything a bit nicer, it's not needed.

The Tailwind UI license will unfortunately prevent peoples implementations of that from being shared though.