Support projects using lein-shadow

[PEZ]

There is a Leiningen plugin that allows you to use lein for controlling shadow-cljs watches and builds.

While I think it actually works to use Calva's shadow-cljs project type, which uses shadow-cljs directly, that will render a warning from shadow-cljs about it skipping any dependencies listed in shadow-cljs.edn file (since, if it is correctly configured, it contains :lein true and then deps are handled from there).

Calva should support this project setup more explicitly, I think. That will make it easier to understand how to use Calva for these projects. This is extra important since this is what you will get if you create a fresh Luminus project with +shadow-cljs.