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.

core/core.el

@@ -477,6 +477,14 @@ If this is a daemon session, load them all immediately instead."
                            (cdr doom-incremental-packages) t))))
 
 
+;;
+;;; Fixes/hacks
+
+;; Produce more helpful (and visible) error messages from errors emitted from
+;; hooks (particularly mode hooks, that usually go unnoticed otherwise.
+(advice-add #'run-hooks :override #'doom-run-hooks)
+
+
 ;;
 ;;; Bootstrapper