Function prepare_depth_of_field_global_bind_group 

pub fn prepare_depth_of_field_global_bind_group(
    global_bind_group_layout: Res<'_, DepthOfFieldGlobalBindGroupLayout>,
    dof_bind_group: ResMut<'_, DepthOfFieldGlobalBindGroup>,
    depth_of_field_uniforms: Res<'_, ComponentUniforms<DepthOfFieldUniform>>,
    render_device: Res<'_, RenderDevice>,
)

Creates depth of field bind group 1, which is shared among all instances of the depth of field shader.