app: clean up the new action search a bit

- order some stuff alphabetically and consistently
- move action from help-actions to dialogs-actions
- fix OS/X menu item fiddling (untested)

app/actions/help-actions.c

@@ -47,13 +47,7 @@ static const GimpActionEntry help_actions[] =
     NC_("help-action", "_Context Help"), "<shift>F1",
     NC_("help-action", "Show the help for a specific user interface item"),
     G_CALLBACK (help_context_help_cmd_callback),
-    GIMP_HELP_HELP_CONTEXT },
-
-  { "help-action-search", GTK_STOCK_FIND,
-    NC_("help-action", "_Search and Run a Command"), "slash",
-    NC_("help-action", "Search commands by keyword, and run them"),
-    G_CALLBACK (help_search_actions_cmd_callback),
-    GIMP_HELP_ACTION_SEARCH_DIALOG }
+    GIMP_HELP_HELP_CONTEXT }
 };