Backported Animal Variants

Adds farm animal variants and updated cow model introduced in 1.21.5:

• Cold Chicken (and its Blue Egg)
• Cold Pig
• Cold Cow
• Warm Chicken (and its Brown Egg)
• Warm Pig
• Warm Cow
• Cow, Mooshroom model update
• Sheep texture update

You can report bugs or share your suggestions on my Discord server.