fix(vertico): unreachable function in autoloads

+ Rename +vertico--embark-target-package to
  +vertico-embark-target-package-fn to conform to naming conventions,
  and because it's not a private function anymore.
+ Fix +vertico-embark-target-package-fn's indentation.

Fix #5208

modules/completion/vertico/autoload/vertico.el

@@ -103,7 +103,8 @@ If ARG (universal argument), include all files, even hidden or compressed ones."
                      (expand-file-name new-path))))))
       (call-interactively 'backward-delete-char))))
 
-(defun +vertico--embark-target-package ()
+;;;###autoload
+(defun +vertico-embark-target-package-fn ()
   "Targets Doom's package! statements and returns the package name"
   (when (or (derived-mode-p 'emacs-lisp-mode) (derived-mode-p 'org-mode))
     (save-excursion

modules/completion/vertico/config.el

@@ -152,7 +152,7 @@ overrides `completion-styles' during company completion sessions.")
                  (length embark-target-finders))))
     (cl-callf2
         cons
-        '+vertico--embark-target-package
+        '+vertico-embark-target-package-fn
         (nthcdr pos embark-target-finders)))
   (setq embark-package-map (make-sparse-keymap))
   (map! (:map embark-file-map