[AIRFLOW-5153] Option to force delete non-empty BQ datasets

[mohannadbanayosi]

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Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title. For example, "[AIRFLOW-XXX] My Airflow PR"
  • https://issues.apache.org/jira/browse/AIRFLOW-5153

Description

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This extra bool argument gives the option to delete a non-empty Google BigQuery dataset as well as its tables.

Tests

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  6. Body explains "what" and "why", not "how"

Documentation

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Code Quality

• Passes flake8

[kaxil]

LGTM