Support format: json config using @langchain/community/llms/bedrock

[fuleinist]

Checked

• I searched existing ideas and did not find a similar one
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• I've clearly described the feature request and motivation for it

Feature request

In @langchain/ollama, we can set up format: 'json' as per below:

import { Ollama } from '@langchain/ollama';
const ollama = new Ollama({
  ...
  format: 'json',
  ...
});

So that it will enforce output in json format.

It would be great if we can do the same with bedrock per:

import { Bedrock } from '@langchain/community/llms/bedrock';
const bedrock = new Bedrock({
  ...
  format: 'json',
  ...
});

Motivation

Running project with Ollama locally and now trying to move it to AWS Bedrock but facing issue to force json output

Proposal (If applicable)

Adding support for format: json in @langchain/community/llms/bedrock the same way as @langchain/ollama