`star-*-with-alpha.avifs` files have wrong alpha image item reference

[farindk]

The AVIFS files with alpha (star-*-with-alpha.avifs) not only have sequence tracks, but also a still image with an attached auxiliary alpha image.
The problem is that the iref associating the alpha image to the color image has a zero item ID instead of the color image ID:

| Box: iinf ----- (Item Information)
| size: 66   (header size: 12)
| | Box: infe ----- (Item Info Entry)
| | size: 26   (header size: 12)
| | item_ID: 3
| | item_protection_index: 0
| | item_type: av01
| | item_name: Alpha
| | hidden item: false
| | 
| | Box: infe ----- (Item Info Entry)
| | size: 26   (header size: 12)
| | item_ID: 4
| | item_protection_index: 0
| | item_type: av01
| | item_name: Color
| | hidden item: false
| 
| Box: iref ----- (Item Reference)
| size: 26   (header size: 12)
| reference with type 'auxl' from ID: 3 to IDs: 0             <<<<<<<<<<<<<<<<<<<<<<