Feature request: Add support for self masking of semi-transparent materials.

I have a fish model, with some parts of its texture being transparent:

The problem is, when these faces are put in front of other faces from the same object, the transparent part hides them instead of displaying over it:

This makes it impossible to look through the transparent part. This problem does not seem to happen when rendering the transparent faces over faces of a different object, but I can't just manually separate every single element into multiple objects because these models are automatically exported and there's 160 of them.

The model I used: [Sardine.zip](https://github.com/user-attachments/files/23690197/Sardine.zip)

Reproduce the issue in the glTF-Sample-Viewer using the attached Sardine.zip model, then trace the rendering path responsible for transparent materials. Done means semi-transparent faces from the same object no longer hide faces behind them, while the existing behavior for separate objects remains intact.

Written by the indexing model from the issue text.