Anvil text field does not support translucent textures

More loosely relates to these issues: MC-144009 MC-145821 MC-164001 MC-165403

The bug

If translucent pixels are present in any of the two sprites for the anvil text field, they are rendered completely opaque in-game, which is not correct.

How to reproduce

1. Download and apply the attached resource pack
2. Enter an anvil
3. Observe

Expected results

Translucent textures where the text is.

Actual results

Entirely opaque.