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/ui/workspaces/config.el

@@ -118,7 +118,7 @@ stored in `persp-save-dir'.")
   (add-to-list 'persp-add-buffer-on-after-change-major-mode-filter-functions
                #'doom-unreal-buffer-p)
 
-  (def-advice! +workspaces-evil-alternate-buffer-a (&optional window)
+  (defadvice! +workspaces--evil-alternate-buffer-a (&optional window)
     "Make `evil-alternate-buffer' ignore buffers outside the current workspace."
     :override #'evil-alternate-buffer
     (let* ((prev-buffers