4a95c0405c
`OpenSubdiv_Buffer` is a wrapper that was introduced at the time that Blender couldn't use CPP directly. It contains a pointer to a VertBuf and callbacks to use GPU module on that buffer. This PR replaces OpenSubdiv_Buffer with `blender::gpu::VertBuf` and removes the wrapper. NOTE: OpenSubdiv tests are added to blender_test executable to make the library dependencies not to complicated. Pull Request: https://projects.blender.org/blender/blender/pulls/135389