Semi-Transparent Shader Support

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### Proposed new feature or change

I am trying to render a tree that has textures. The model is broken into two meshes (one for the branches, and the other for all the leaves)

The problem is that when I render the tree using the "defaultLitTransparency", it means that any leaf points behind the transparent area disappear. I have attached an image showing what happens when I use the "defaultLitTransparency" as-well as the "defaultLit" shader.

I have done a bit of investigation and have seen that the depthWrite needs to be enabled within the shader.



### References

_No response_

### Additional information

_No response_