Add vanilla entity models

[MiraculixxT]

Add more entity models to the new entity renderer by BlueMap. Draft until most entities are covered (or i run out of time)

Entities in this PR

• Chicken (adult/baby)
• Pig (adult/baby)
• Cod
• Salmon
• Tropical fish
• Pufferfish
• Bee (adult/baby)
• Llama (all variants + chest, missing carpet)
• Fox (orange, white, missing baby)

[TBlueF]

I allowed myself to commit a proposal in here on how to handle the entity-data based models for now: =)

I think i prefer handling it in this (hardcoded) way for now, instead of inventing an entirely new and complex data-driven model. Mostly because a data-driven approach would:

• still need a ton of hardcoded helpers/value-loaders to load the correct state/data from a specific entity-type
• be overly complex to implement
• most likely overengineered for the actual use it would be (i don't expect many resource-packs actively supporting bluemaps custom entity-model format)

Also if/once mojang decides to add an official data-driven format for entity-models, we will need to switch to that.

I think this "hardcoded" way of adding a simple custom renderer per entity-type is the easiest and most flexible way right now :)

Any thoughts about this are still very welcome!