💥 revise hook/var fns naming convention (2/2)

This is second of three big naming convention changes. In this commit,
we change the naming conventions for hook functions and variable
functions:

1. Replace the bar | to indicate a hook function with a -h suffix, e.g.

     doom|init-ui -> doom-init-ui-h
     doom|run-local-var-hooks -> doom-run-local-var-hooks-h

2. And add a -fn suffix for functions meant to be set on variables,
   e.g.

     (setq magit-display-buffer-function #'+magit-display-buffer-fn)

See ccf327f8 for the reasoning behind these changes.

core/autoload/fonts.el

@@ -65,6 +65,15 @@ FRAME parameter defaults to current frame."
 ;;
 ;;; Commands
 
+;;;###autoload
+(defun doom/reload-font ()
+  "Reload your fonts, if they're set.
+See `doom-init-fonts-h'."
+  (interactive)
+  (when doom-font
+    (set-frame-font doom-font t))
+  (mapc #'doom-init-emoji-fonts-h (frame-list)))
+
 ;;;###autoload
 (defun doom/increase-font-size (count)
   "Enlargens the font size across the current frame."