Create a jank REPL server

[jeaye]

We need to figure out what goes into making editor-friendly REPL servers and cook one up. I think it makes the most sense to write it in jank itself, to dogfood sufficiently. I don't think existing Clojure REPL servers can work, but this should also be investigated.

As I intend for jank to be a monorepo of official tools, this project should be merged into main eventually.

This is blocked on #31 and work with native boxes (sockets, mainly).