Support custom weights for RT

[Delamare2112]

When using custom training data, I believe that the weights parameter needs to be set using the void oidnSetSharedFilterData(OIDNFilter filter, const char* name, void* ptr, size_t byteSize); call. Just like albedo and normal but with data instead of an image.

https://github.com/OpenImageDenoise/oidn/blob/v1.2.4/README.md#filter
https://github.com/OpenImageDenoise/oidn/blob/v1.2.4/README.md#rt

[Twinklebear]

This would be good to have in, I'll add it to the todo list.