core[patch]: Allow dynamic tools to be initialized with JSON schema

[jacoblee93]

If you init a tool with JSON schema, it will not currently validate/infer any types.

Types are starting to get pretty hairy in general but I've added some tests around them.

CC @bracesproul @nfcampos

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[debajyoti-truefoundry]

@jacoblee93 I tried using this feature with the ReAct agent but realized the JSON schema was not passed on to the OpenAI request.

https://github.com/dkundel/langchainjs/blob/9ec46a2f4d4598bbca4b97034b63cde4146d8809/langchain-core/src/tools/index.ts#L432

    '  "tools": [\n' +
    '    {\n' +
    '      "type": "function",\n' +
    '      "function": {\n' +
    '        "name": "postModel",\n' +
    '        "description": "Model",\n' +
    '        "parameters": {\n' +
    '          "type": "object",\n' +
    '          "properties": {},\n' +
    '          "additionalProperties": true,\n' +
    '          "$schema": "http://json-schema.org/draft-07/schema#"\n' +
    '        }\n' +
    '      }\n' +
    '    },\n' 

Even though there will be no validation, the JSON Schema should at least be forwarded to the model invocation. It would be helpful if you could let me know what the expected behaviour is here.