Contents Menu Carousel parsed incorrectly

[FyreByrd]

There are two issues so far that have surfaced when tweaking the contents menus in the web_gospels_nested test project:

1. visible-items is not respected. The test project has a value of 3 for visible-items in the carousel, but only two items are available.
2. Adding a fourth item to the carousel in the test project causes some really weird unexpected issues.

• I added a fourth item with a subtitle to the carousel.
• The same subtitle was somehow duplicated as a subtitle to the heading for the carousel, which does not have a heading defined in SAB.
• As best as I can tell, this may be because the carousel is the fourth contents menu item, and so the conversion process somehow got confused because both items had 4 as the id.
• The issue itself also surfaced because the PWA does not respect when the contents menu item has a heading value set to false