[FEATURE] Support predict API, it is missing although is in the API spec

The predict API is not represented in the Java client, and this would be used heavily if you are doing actions such as caching embeddings outside of indexing and ingest pipeline.

https://docs.opensearch.org/latest/ml-commons-plugin/api/train-predict/predict/

This is in the opensearch-openapi.yaml file

  /_plugins/_ml/_predict/{algorithm_name}/{model_id}:
    post:
      operationId: ml.predict.0
      x-operation-group: ml.predict
      x-version-added: '1.3'
      description: Predicts new data with trained model.
      parameters:
        - $ref: '#/components/parameters/ml.predict___path.algorithm_name'
        - $ref: '#/components/parameters/ml.predict___path.model_id'
        - $ref: '#/components/parameters/_global___query.pretty'
        - $ref: '#/components/parameters/_global___query.human'
        - $ref: '#/components/parameters/_global___query.error_trace'
        - $ref: '#/components/parameters/_global___query.source'
        - $ref: '#/components/parameters/_global___query.filter_path'
      requestBody:
        $ref: '#/components/requestBodies/ml.predict'
      responses:
        '200':
          $ref: '#/components/responses/ml.predict___200'

but not in generated code. Other related methods might be missing.

Start with the predict endpoint definition in opensearch-openapi.yaml and inspect how that specification becomes generated Java client code. Trace a comparable existing ML API method, then verify that the predict operation, path parameters, request body, and response are exposed in the client.