Feature/define partition for bigquery import

[pbonito]

Hi,
I made some changes to allow partitioning when importing data into a BigQuery table.
The feature can be activated with the following configuration:

BigQueryTimePartitioning bigQueryTimePartitioning = new BigQueryTimePartitioning();
bigQueryTimePartitioning.setType("DAY");
configuration.set(BigQueryConfiguration.OUTPUT_TABLE_PARTITIONING_KEY, bigQueryTimePartitioning.getAsJson());

Regards

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[medb]

Thank you for contribution!

Please, use https://github.com/google/google-java-format to format this PR.

[pbonito]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

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[pbonito]

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I signed it!

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[pbonito]

I signed it!

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[functicons]

Thanks!

[medb]

Thank you for contribution!