Implements #168 keeping decoding on GPU

IMPORTANT: Requires a custom build of nvpipe due to bug in nvpipe.

components/codecs/include/ftl/codecs/nvpipe_decoder.hpp

@@ -25,6 +25,7 @@ class NvPipeDecoder : public ftl::codecs::Decoder {
 	MUTEX mutex_;
 	bool seen_iframe_;
 	cv::cuda::GpuMat tmp_;
+	cv::cuda::Stream stream_;
 };
 
 }