💥 Refactor add-hook! macro & change arg order

This update may potentially break your usage of add-hook! if you pass
the :local or :append properties to it. This is how they used to work:

  (add-hook! :append 'some-mode-hook #'do-something)

Thsoe properties must now follow the hooks, e.g.

  (add-hook! 'some-mode-hook :append #'do-something)

Other changes:
- Various add-hook calls have been renamed to add-hook! because I
  incorrectly assumed `defun` always returned its definition's symbol,
  when in fact, its return value is "undefined" (so sayeth the
  documentation). This should fix #1597.
- This update adds the ability to add multiple functions to hooks
  without a list:

    (add-hook! 'some-mode-hook
               #'do-something
               #'do-something-else)

- The indentation logic has been changed so that consecutive function
  symbols at indented at the same level as the first argument, but forms
  are indent like a defun.

    (add-hook! 'some-mode-hook
               #'do-something
               #'do-something-else)

    (add-hook! 'some-mode-hook
      (message "Hello"))

modules/lang/csharp/config.el

@@ -19,12 +19,12 @@
   (setq omnisharp-auto-complete-want-documentation nil
         omnisharp-cache-directory (concat doom-cache-dir "omnisharp"))
   :config
-  (defun +csharp|cleanup-omnisharp-server ()
+  (defun +csharp-cleanup-omnisharp-server-h ()
     "Clean up the omnisharp server once you kill the last csharp-mode buffer."
     (unless (doom-buffers-in-mode 'csharp-mode (buffer-list))
       (omnisharp-stop-server)))
-  (add-hook! csharp-mode
-    (add-hook 'kill-buffer-hook #'+csharp|cleanup-omnisharp-server nil t))
+  (add-hook! 'csharp-mode-hook
+    (add-hook 'kill-buffer-hook #'+csharp-cleanup-omnisharp-server-h nil t))
 
   (set-company-backend! 'csharp-mode 'company-omnisharp)
   (set-lookup-handlers! 'csharp-mode