org-next-visible-heading: Fix when moving over non-descriptive link

* lisp/org.el (org-next-visible-heading): Really test for visibility;
not folding.  Some folds may not be invisible - when
`org-link-descriptive' is nil, links are folded yet visible.
* testing/lisp/test-org.el (test-org/next-visible-heading): Add new
test case.

Reported-by: Rudolf Adamkovič <salutis@me.com>
Link: https://orgmode.org/list/m2bk9q7adw.fsf@me.com

lisp/org.el

@@ -21389,13 +21389,13 @@ With ARG, repeats or can move backward if negative."
       (end-of-line))
     (while (and (< arg 0) (re-search-backward regexp nil :move))
       (unless (bobp)
-	(when (org-fold-folded-p)
+	(when (org-invisible-p nil t)
 	  (goto-char (org-fold-previous-visibility-change))
           (unless (looking-at-p regexp)
             (re-search-backward regexp nil :mode))))
       (cl-incf arg))
     (while (and (> arg 0) (re-search-forward regexp nil :move))
-      (when (org-fold-folded-p)
+      (when (org-invisible-p nil t)
 	(goto-char (org-fold-next-visibility-change))
         (skip-chars-forward " \t\n")
 	(end-of-line))

testing/lisp/test-org.el

@@ -4069,7 +4069,13 @@ text"
   (should
    (org-test-with-temp-text "* H1\n* H2\n<point>* H3"
      (org-next-visible-heading -2)
-     (looking-at "\\* H1"))))
+     (looking-at "\\* H1")))
+  ;; Edge case: visible links.
+  (should
+   (let ((org-link-descriptive nil))
+     (org-test-with-temp-text "* <point>H1\n* [[https://orgmode.org][Org mode]]\n* H3"
+       (org-next-visible-heading 1)
+       (looking-at "\\* \\[\\[https:")))))
 
 (ert-deftest test-org/previous-visible-heading ()
   "Test `org-previous-visible-heading' specifications."