Add horse armour hack

[Protonull]

This optionally allows players to craft iron, gold, and diamond horse armour like so:

The idea being you're taking Leather Horse Armour, which is already craftable, and plating it. But this can be changed.

Horse armour has the unique quality of being invincible, so this hack optionally reimplements durability. This is somewhat hacky though since the client has no idea about this and wont show a durability bar. Open to suggestions on how this could be resolved.

Since horse armour is invincible, the Unbreaking enchant has no effect, so this hack optionally reimplements Unbreaking.

[Protonull]

This is somewhat hacky though since the client has no idea about this and wont show a durability bar.

This'll be resolved with 1.20.5 with the help of item components. It only currently means displaying an durability bar on the item stack, but hopefully Mojang will expand support so that combat damages any item with a damageable component, rather than just predefined items.