Delete trailing whitespace, globally, by default

Also adds doom|disable-delete-trailing-whitespace hook, which can be
used to disable this behavior on a per-buffer basis. If you want to turn
off this global behavior:

  (remove-hook 'write-file-functions #'delete-trailing-whitespace)

modules/lang/racket/config.el

@@ -18,12 +18,7 @@
 
   (setq racket-smart-open-bracket-enable t)
 
-  (add-hook! racket-mode
-    #'(;; 3rd-party functionality
-       doom|enable-delete-trailing-whitespace
-       ;; fontification
-       rainbow-delimiters-mode
-       highlight-quoted-mode))
+  (add-hook! racket-mode #'(rainbow-delimiters-mode highlight-quoted-mode))
 
   (map! :map racket-mode-map
         :localleader