refactor: switch buffer/frame/window hooks

Emacs 27 introduced a bunch of `window-*-change-functions` hooks,
including `window-selection-change-functions` and
`window-buffer-change-functions`, which handles 98% of the use case for
Doom's `doom-switch-{buffer,window,frame}-hook` hooks, so I've rewritten
them to use them under the hood, which amounts to simpler code and fewer
hacks.

modules/ui/hydra/config.el

@@ -11,5 +11,5 @@
 
 (defadvice! +hydra--inhibit-window-switch-hooks-a (fn)
   :around #'lv-window
-  (let ((doom-inhibit-switch-window-hooks t))
+  (let (doom-switch-window-hook)
     (funcall fn)))