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/lang/org/contrib/dragndrop.el

@@ -22,7 +22,7 @@
   ;; Handle non-image files a little differently. Images should be inserted
   ;; as-is, as image previews. Other files, like pdfs or zips, should be linked
   ;; to, with an icon indicating the type of file.
-  (def-advice! +org-dragndrop-insert-link-a (_link filename)
+  (defadvice! +org--dragndrop-insert-link-a (_link filename)
     "Produces and inserts a link to FILENAME into the document.
 
 If FILENAME is an image, produce an attach:%s path, otherwise use file:%s (with
@@ -50,7 +50,7 @@ an file icon produced by `+org-attach--icon')."
                     (file-name-nondirectory (directory-file-name filename)))))))
 
   (advice-add #'org-download--dir-2 :override #'ignore)
-  (def-advice! +org-dragndrop-download-fullname-a (path)
+  (defadvice! +org--dragndrop-download-fullname-a (path)
     "Write PATH relative to current file."
     :filter-return #'org-download--fullname
     (let ((dir (or (if buffer-file-name (file-name-directory buffer-file-name))