trolled by a noise_level input. A higher
noise_level increases the variance in the final un-noised images.
The noise is applied in two ways
A noise schedule is applied directly to the embeddings
A vector of sinusoidal time embeddings are appended to the output.
In both cases, the amount of noise is controlled by the same noise_level.
The embeddings are normalized before the noise is applied and un-normalized after the noise is applied.
