BigQuery: Add maximum_bytes_billed option to magics #7678

Background

BigQuery queries can get expensive, but the maximum_bytes_billed query option adds a cap to the price billed and rejects queries that could be too expensive. Provide a default value for maximum_bytes_billed when constructing a client by specifying a default_query_job_config, but this is not possible when using the %%bigquery magics.

Feature Request

Add a --maximum_bytes_billed option to %%bigquery. Possible values:

• UNSPECIFIED - Use the default value . Set job_config.maximum_bytes_billed = google.cloud.bigquery.magics.context.maximum_bytes_billed.
• --maximum_bytes_billed=None - No maximum value. Set job_config.maximum_bytes_billed = None. This allows all queries to run, overriding any value from the global context.
• --maximum_bytes_billed=123456789 - Set maximum to value specified. Set job_config.maximum_bytes_billed = int(value).
• --maximum_bytes_billed=NotAnInteger - Raise ValueError.