Improve deps.edn and Leiningen + shadow-cljs project support

[PEZ]

The connect sequences involving deps.edn or Leiningen + shadow-cljs often cause troubles for people. I think it is due to that shadow-cljs dependencies are assumed to be present.

Many of these projects are configured so that shadow-cljs uses deps.edn or Leiningen for dependencies and then it is a better Calva workflow to start them that way. I think we can improve the documentation to help with this a bit. But we should also look at how the Jack-in process can guide better. And when the dependencies are not met, we need better error messaging (or inject the dependency, which I am a bit hesitant to do, because we used to inject Figwheel dependencies and that caused troubles in other ways).

Two related issues:

• v2.0.210: Jack-In with fixed deps.edn + shadow-cljs fails starting cljs REPL #1285
• Cannot jack-in to deps.edn + shadow-cljs project #1307

Here's a thread illustrating where the current state of affairs cause confusion: https://clojureverse.org/t/understanding-jack-in-in-calva/

[PEZ]

I think this is mostly taken care of by now.