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/javascript/config.el

@@ -52,7 +52,7 @@
     mode-name "JS2")
 
   (set-electric! 'js2-mode :chars '(?\} ?\) ?. ?:))
-  (set-repl-handler! 'js2-mode #'+javascript/repl)
+  (set-repl-handler! 'js2-mode #'+javascript/open-repl)
 
   (map! :map js2-mode-map
         :localleader