docs(convo): add new fields and make corrections on caching

[sicoyle]

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Description

Doc updates for conversation API new fields for response format, prompt cache, usage metrics, and model return on conversation api.

Runtime: dapr/dapr#9241
Python SDK dapr/python-sdk#902
Go SDK dapr/go-sdk#801
Quickstarts: dapr/quickstarts#1283

Issue reference

[marcduiker]

LGTM