Image to Image (refinement)

[jeffhandley]

Add APIs to support editing/refining images by providing the existing image and a prompt for the refinements..

[ericstj]

This is already covered in #6648

[ericstj]

This is complete with #6648. Will let #6641 cover addressing the documentation.

We added basic support for edit. This does not yet cover advanced scenarios, but those could hypothetically be plumbed through as options. We will need to see which common patterns immerge.