[Blocking] Armour Model does not support Hat layer

Version:
1.2.9 662590

Summary:
The armour model does not support a hat layer. If the armour has a texture for a hat layer it is not rendered when equipped on a player/armourstand. This deviates from how java works.

Impact:
If the armour has a texture for a hat layer it is not rendered when equipped. Armours which require a hat layer therefore cannot be used. This blocks a piece of content for the Noxcrew

Repro Steps:
1. Create a new world, with cheats enabled
2. Equip the attached texture pack
3. Change gamemode to creative
4. Give the player gold armour and equip it
5. Obverse the helmet texture

Observed results:
The texture file has a hat layer. It is not rendered due the armour model in mobs.json not referring to a 'hat' bone. The armour model uses the parent of the zombie which does list a hat bone. The armour stand model does not have a hat bone either. Due to the limitation of not being able to create new bones and the hat layer not being referred to by default, the armour models do not use a hat layer and it cannot be added through modifying model.

Expected results:
The model "geometry.humanoid.armor1:geometry.zombie" references the 'hat' bone. The zombie and amour both do not have hat textures by default so would not affect them. However it would allow for hat layers to be used for custom textures, similar to Java. A likewise change of adding a hat bone to the armour stand too.

Screenshots/videos attached:
The texture pack shown, the texture in Java, the same texture in bedrock and highlighted the proposed fix for player equipped armour. The red line uses the hat lay, in java it is visible whereas in bedrock it is not