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**Description**

DatabricksRunNowOperator is missing the option to take in key word arguement _jar_params_ , it already can take the other ones notebook_params,python_params,spark_submit_params. https://docs.databricks.com/dev-tools/api/latest/jobs.html#run-now


**Use case / motivation**

Provide parity with the other options

airflow/providers/databricks/operators/databricks.py
- ``timeout_seconds``
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:DatabricksSubmitRunOperator`
    :param json: A JSON object containing API parameters which will be passed
        directly to the ``api/2.0/jobs/runs/submit`` endpoint. The other named parameters
        (i.e. ``spark_jar_task``, ``notebook_task``..) to this operator will
        be merged with this json dictionary if they are provided.
        If there are conflicts during the merge, the named parameters will
        take precedence and override the top level json keys. (templated)
        .. seealso::
            For more information about templating see :ref:`concepts:jinja-templating`.
            https://docs.databricks.com/api/latest/jobs.html#runs-submit
    :type json: dict
    :param spark_jar_task: The main class and parameters for the JAR task. Note that
        the actual JAR is specified in the ``libraries``.
        *EITHER* ``spark_jar_task`` *OR* ``notebook_task`` *OR* ``spark_python_task``
        *OR* ``spark_submit_task`` should be specified.
        This field will be templated.
        .. seealso::
            https://docs.databricks.com/api/latest/jobs.html#jobssparkjartask
    :type spark_jar_task: dict
    :param notebook_task: The notebook path and parameters for the notebook task.
        *EITHER* ``spark_jar_task`` *OR* ``notebook_task`` *OR* ``spark_python_task``
        *OR* ``spark_submit_task`` should be specified.
        This field will be templated.
        .. seealso::
            https://docs.databricks.com/api/latest/jobs.html#jobsnotebooktask
    :type notebook_task: dict
    :param spark_python_task: The python file path and parameters to run the python file with.