feat(format): add :lang racket formatter

modules/lang/racket/config.el

@@ -21,6 +21,7 @@
     :dot     ".")
   (set-rotate-patterns! 'racket-mode
     :symbols '(("#true" "#false")))
+  (set-formatter! 'raco-fmt '("raco" "fmt") :modes '(racket-mode))
 
   (add-hook! 'racket-mode-hook
              #'rainbow-delimiters-mode

modules/lang/racket/doctor.el

@@ -9,3 +9,8 @@
 
 (unless (executable-find "raco")
   (warn! "Could not find raco executable; commands for install packages and build libraries will not work."))
+
+(when (modulep! :editor format)
+  (unless (and (executable-find "raco")
+               (eq 0 (call-process-shell-command "raco fmt --help" nil nil)))
+    (warn! "Couldn't find raco fmt. Formatting will be disabled.")))