vulkan/video: video session parameters should be deep copied?
We don't currently deep copy the video session objects, but the spec suggests we should
"If pCreateInfo->videoSessionParametersTemplate is not VK_NULL_HANDLE, then each StdVideoH264SequenceParameterSet entry stored in it is copied to the created video session parameters object if the created object does not already contain such an entry with the same seq_parameter_set_id."
this might require a rethink of how we store things.