patch 8.2.0748: cannot get a list of all popups

Problem:    Cannot get a list of all popups.
Solution:   Add popup_list().  Use it in the test runner.

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    748,
 /**/
     747,
 /**/