Allow stream listener to work on any type

[chenmoneygithub]

Previously we limit stream listeners to only work with str field and some prebuilt types. This PR lifts up the constraint, and allow streaming on any types. Here is the gist:

• StreamLIstener works the same way as before, i.e., only capture streaming chunks associated with a certain field.
• We don't perform additional handling on the structured output value for each field, but just give back the value.

To accomodate JSONAdapter, which doesn't have clear boilerplate like [[ ## answer ## ]] that splits the fields' streaming in ChatAdapter, we make specific logic chunk based on jiter to handle it.