Builds a one-off GPU-side texture with no source data — a depth buffer,
an off-screen render target — and hands back its
TextureView. Unlike TextureDescriptor,
which loads pixel data from a file/bytes through the asset pipeline,
this allocates an empty texture directly; there’s nothing to upload.
A wgpu::TextureView, opaque — the FrameOperations::Attachment/
DepthAttachment
type for WGPUBackend, and TextureBuilder::build’s return type.
Bundles the backing wgpu::Texture alongside the view (kept alive,
never otherwise accessed) — the view alone isn’t enough to keep the
underlying resource alive for as long as it’s needed.