377: Update with minBufferBindingSize r=cwfitzgerald a=kvark
Depends on https://github.com/gfx-rs/wgpu/pull/726
Also reverts #373 : buffer bindings now have to include at least one element of an unsized struct portion, so they can't be zero-sized.
Co-authored-by: Dzmitry Malyshau <kvarkus@gmail.com>