Makes the Beds sprites when inside of your inventory.
The sprites are
based pretty much exactly the same as the sprites from Bedrock/PS4 Editions. off of
This makes use of 2 things from 1.14's CustomModelData tag.
1. Items textures can be applied to blocks using it (but only in the inventory/hand)
2. setting an item to be CustomModelData:0 will replace the item's texture when inside of your inventory
That's how the resource pack works.