Impossible to use auxiliary buffers with oidn_wgpu_interop

[LeonardoTemperanza]

In my opinion having the filter own the auxiliary buffers is unintuitive. As far as I can tell it also makes it impossible to use with oidn_wgpu_interop, as shared oidn buffers can only be obtained by reference. I'd like to know if there's something I'm missing, otherwise I'd like to possibly rework this.