[AIRFLOW-4287] location support for BigQueryGetDataOperator

[yohei1126]

Jira

• https://issues.apache.org/jira/browse/AIRFLOW-4287
• This is 1/10 operators needs to be fixed to support location. See here for full list https://issues.apache.org/jira/browse/AIRFLOW-3601

Description

• Add location support to BigQueryGetDataOperator. location is required if you run this operator in the region except US and EU.

Tests

• My PR adds the following unit tests
• tests/contrib/hooks/test_bigquery_hook.py
• tests/contrib/operators/test_bigquery_get_data.py

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• In case of new functionality, my PR adds documentation that describes how to use it.
  • All the public functions and the classes in the PR contain docstrings that explain what it does
  • If you implement backwards incompatible changes, please leave a note in the Updating.md so we can assign it to a appropriate release

Code Quality

• Passes flake8

[kaxil]

Why are we not doing this as part of #4448 ?

[yohei1126]

please continue one by one

[kaxil]

@yohei1126 - Can we please do it one, it is easier for review + it is a single piece of work that would be included in next release?