Add Support for List[Image]

[ryanh-ai]

When providing List[dspy.Image] for input field, the ChatAdapter was formatting the list of images as a string and overflowing the input context for LM's from multiple providers.

Changes were done very quickly to unblock active work, but this is tested locally across Bedrock and OpenAI providers.

[ryanh-ai]

@isaacbmiller FYI, per Discord thread on this issue

[okhat]

Thanks a ton @ryanh-ai ! I guess in general do we need more complex collections of images? Will people also want to do dict[str, list[Image]] and all kinds of crazy things?

If we only wanna support list[Image], then this PR is good if @isaacbmiller approves it.

[isaacbmiller]

I think that people will at a minimum want to do things like dict[str, Image] which I am not sure even works currently.

I think this PR shouldn't be merged and I can work on a scalable solution for adapters for all different types including Image

[ryanh-ai]

Agree above on the likely need for dictionary support.

I also found an edge case when length of image list is 1. I will update the patch when I adjust that, but not invest too much more in this until you determine best path forward. I'm happy to test as you do!