[ModelDoc] Models with certain invisible 'tool' materials won't render bonemerged models in ModelDoc

[Gmod4phun]

Describe the bug

Might be related to #3908 . Models that use certain tool textures become invisible, and models bonemerged to them will not render inside of ModelDoc. An example is an adapter model for hands, which I used the toolsinvisible material on. The mesh is just a simple cube, which I hide by applying the invisible material to it, then bonemerge the arms model to it. Inside modeldoc, the bonemerged models are also invisible, but they do work fine in-game. Making a custom 'invisible' material works fine in both ModelDoc and in-game.

https://github.com/sboxgame/issues/assets/5991682/4c7cb4f6-dad5-4eb2-ba90-6bb2155b0691

To Reproduce

1. Have a model with one of the tool materials that make it invisible
2. Bonemerge other models to it in ModelDoc
3. Observe that the bonemerged models are invisible

Expected behavior

The bonemerged models should not be affected and should render properly.

Media/Files

No response

Additional context

No response

[handsomematt]

Not sure what your goal is here, but tools materials are really only intended for use with Hammer.

[Gmod4phun]

I know, but in the rare case that anyone uses them on a model in ModelDoc, it probably should not cause bonemerged items to not render.