Add csv upload support for BigQuery (#7756)

* Add extra_require for bigquery to setup.py

* Refactor df_to_db and add df upload capability for BigQuery

* Fix unit tests and clarify kwarg logic

* Fix flake8 errors

* Add minimum versions for bigquery dependencies

* wrap to_gbq in try-catch block and raise error if pandas-gbq is missing

* Fix linting error and make error more generic

setup.py

@@ -108,6 +108,10 @@ setup(
         'wtforms-json',
     ],
     extras_require={
+        'bigquery': [
+            'pybigquery>=0.4.10',
+            'pandas_gbq>=0.10.0',
+        ],
         'cors': ['flask-cors>=2.0.0'],
         'hive': [
             'pyhive[hive]>=0.6.1',