Possible variants of the DiffusionSampling environment to add

[josephdviviano]

The diffusion sampling environment itself is general enough. Defining a new target distribution would be enough for most cases.

A few interesting variants of the environment are:

• Conditional sampling (e.g., VAE)
  • relatively easy to implement
• Fine-tuning (e.g., RTB, outsourced diffusion, and outsourced Schrodinger bridge)
  • requiring much more work

Originally posted by @hyeok9855 in #419 (comment)