Add timestamp, provider & model information in message metadata (road-core#330)

* add metadata in chat history

Signed-off-by: Stephanie <[email protected]>

* fix test failure

Signed-off-by: Stephanie <[email protected]>

* regenerate openapi json

Signed-off-by: Stephanie <[email protected]>

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Signed-off-by: Stephanie <[email protected]>

Author: yangcao77