Add use_table_schema parameter for PubSub subscription to BigQuery

[mdaddetta]

Hello team,

the current pull request is defined in order to add the usage of use_table_schema argument in Pub/Sub module.
The parameter is used in subscription definition and enables to write data to BigQuery tables using the table schema.

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Checklist

I applicable, I acknowledge that I have:

• Read the contributing guide
• Ran terraform fmt on all modified files
• Regenerated the relevant README.md files using tools/tfdoc.py
• Made sure all relevant tests pass

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[ludoo]

Thanks!