**Description**

`BigQueryInsertJobOperator` requires the submission of a `configuration` parameter in the form of a dict.  Unfortunately, if this contains a large SQL query - especially one that is formatted with new lines - then this cannot currently be rendered very nicely in the UI.

<img width="1670" alt="Screenshot 2021-07-15 at 15 39 33" src="https://user-images.githubusercontent.com/967119/125806943-839d57a9-d4a0-492d-b130-06432b095239.png">

**Use case / motivation**

The issue with this is that it's impossible to copy and paste the rendered query out of the Airflow UI, into a BigQuery browser and run it without lots of manual edits which is time wasted when troubleshooting problems.

**Are you willing to submit a PR?**

Yes.  My current thought process around this would be to add an optional SQL parameter to the operator which, if provided, would be added into the configuration and could therefore have its own template field and SQL renderer.

e.g.

<img width="1570" alt="Screenshot 2021-07-14 at 14 18 09" src="https://user-images.githubusercontent.com/967119/125808200-5f30b8f4-4def-48a7-8223-82afdc65c973.png">


airflow/providers/google/cloud/operators/bigquery.py
self.dataset_reference = dataset_reference if dataset_reference else {}
        self.delegate_to = delegate_to
        self.impersonation_chain = impersonation_chain
        self.exists_ok = exists_ok
        super().__init__(**kwargs)
    def execute(self, context) -> None:
        bq_hook = BigQueryHook(
            gcp_conn_id=self.gcp_conn_id,
            delegate_to=self.delegate_to,
            location=self.location,
            impersonation_chain=self.impersonation_chain,
        )
        try:
            bq_hook.create_empty_dataset(
                project_id=self.project_id,
                dataset_id=self.dataset_id,
                dataset_reference=self.dataset_reference,
                location=self.location,
                exists_ok=self.exists_ok,
            )
        except Conflict:
            dataset_id = self.dataset_reference.get("datasetReference", {}).get("datasetId", self.dataset_id)
            self.log.info('Dataset %s already exists.', dataset_id)
class BigQueryGetDatasetOperator(BaseOperator):
    """
    This operator is used to return the dataset specified by dataset_id.
    .. seealso::
        For more information on how to use this operator, take a look at the guide:
        :ref:`howto/operator:BigQueryGetDatasetOperator`
    :param dataset_id: The id of dataset. Don't need to provide,