def-advice!->defadvice! & conform to new advice conventions

This commit does two things:

- Renames def-advice! to defadvice!, in the spirit of naming convenience
  macros after the function/macro they enhance or replace.
- Correct the names of advice functions to indicate visibility and
  intent. A public advice function like doom-set-jump-a is meant to be
  used elsewhere. A private one like +dired--cleanup-header-line-a
  shouldn't -- it likely won't work anywhere but the function(s) it was
  made to advise.

modules/config/default/+emacs.el

@@ -12,7 +12,7 @@
 (use-package! expand-region
   :commands (er/contract-region er/mark-symbol er/mark-word)
   :config
-  (def-advice! doom--quit-expand-region-a ()
+  (defadvice! doom--quit-expand-region-a ()
     "Properly abort an expand-region region."
     :before '(evil-escape doom/escape)
     (when (memq last-command '(er/expand-region er/contract-region))