Shelf Backport

Adds the new shelf blocks in every variant to Minecraft 1.20.1.

Works with Vanilla Backport (1.20.1 Forge) for the Pale Oak variant.

NOTE: This mod is currently for decoration only. The shelf blocks DO NOT function. I created the mod because I like using the blocks in my builds. I plan to add functionality down the road, but for the time being, they are just another building block.