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/completion/ivy/config.el

@@ -93,7 +93,7 @@ immediately runs it on the current candidate (ending the ivy session)."
   (after! yasnippet
     (add-to-list 'yas-prompt-functions #'+ivy-yas-prompt nil #'eq))
 
-  (def-advice! +ivy--inhibit-ivy-in-evil-ex-a (orig-fn &rest args)
+  (defadvice! +ivy--inhibit-in-evil-ex-a (orig-fn &rest args)
     "`ivy-completion-in-region' struggles with completing certain
 evil-ex-specific constructs, so we disable it solely in evil-ex."
     :around #'evil-ex