Fire overlay is translucent, but fire texture is not

Relates to MC-276496.

The bug

The screen overlay displayed when on fire is translucent, even though the texture for fire itself is not. This applies to all such textures; it is impossible to make the fire overlay appear translucent by use of a resource pack.

How to fix

Remove the hardcoded translucency, and add dedicated, separate translucent textures for the fire overlay.