Update StreamUI to include finishReason, usage, and any other relevant data

[Godrules500]

Feature Description

Currently streamUI does not include finishReason and usage. I'm requesting that it is updated to include those since I am having to revert to streamText to do as I need.

Use Case

1. With google vertex, if it fails for safety violation, there is no way for me to handle it.
2. When the max token limit is reached, I am unable to detect and tell the user that they need to "continue response"

Additional context

No response

[Godrules500]

#1904 Tagging this here as it would solve this.

[gclark-eightfold]

I'll see about pulling-out the onFinish callback into a standalone PR since the other changes in that PR may take a bit longer to review & document.