Allow Clojure code in .calva/config.edn repl and hover snippets

[PEZ]

Calva allows for configuring REPL command and Hover snippets (Clojure code that is evaluated and has some editor context available) via .calva/config.edn. These snippets need today be strings, which takes away a lot of the convenience with configuring them from an EDN file.

We could allow these entries in the config.edn to be code and stringify them, I think.