Update VisualShader page for 4.3

[skyace65]

Updates the visual shader page for Godot 4.3. Also closes #7563.

It still need updates for the last few images. But I also wanted to ask how much people think we need that last section on specific nodes? This page is never going to be a definitive reference on all nodes, the ones we do have images and descriptions for were all added 5 years ago. And most people learning visual shaders in Godot would either be following a tutorial, or have enough existing shader knowledge to know what to look for. I think it might be a good idea to just link to the class reference instead.