langchain_google_vertexai.create_structured_runnable should take a json schema, just like the openAI version

[decision-dev]

Checked

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Feature request

Please add the ability for langchain_google_vertexai.create_structured_runnable to take a json schema or a Sequence of json schema. It currently can only take BaseModel | Sequence[BaseModel]

Motivation

The openAI version of create_structure_runnable can take a json schem or a pydantic v1 BaseModel. The json schema is a great option for those of us who already have our data model in pydantic v2. However, the vertexAI version of create_structured_runnable_cannot take a json schema.

Proposal (If applicable)

No response

[eyurtsev]

cc @baskaryan