Standardize REPL commands & improve SPC o r

- SPC o r now prompts for a REPL to open when none was found for the
  current buffer.
- REPL handlers must now follow the naming convention "*/open*-repl".
  e.g. +python/open-ipython-repl, +emacs-lisp/open-repl, etc.
- +eval/open-repl has been split in two:
  - +eval/open-repl-other-window
  - +eval/open-repl-same-window

modules/lang/lua/autoload.el

@@ -1,7 +1,7 @@
 ;;; lang/lua/autoload.el -*- lexical-binding: t; -*-
 
 ;;;###autoload
-(defun +lua/repl ()
+(defun +lua/open-repl ()
   "Open Lua REPL."
   (interactive)
   (lua-start-process "lua" "lua")