gpui: Support 3D rendering

[shi-yan]

I’m exploring the possibility of implementing a 3D application using GPUI. After reviewing the source code, it appears that GPUI maintains its own scene graph, and developers can only modify this graph, there’s no access to low-level 3D graphics APIs such as Metal, DirectX 12, or Vulkan.

Because of this limitation, creating a full 3D application is currently not feasible.

To experiment with a solution, I extended the existing video-rendering path to support 3D rendering. Since the video surface was hard-coded to use a YUV pixel format, I added support for RGBA as well.

I’ve also put together a proof-of-concept demonstrating this approach.

At the moment, this implementation works only on macOS.

Release Notes:

• N/A