Adding asyncio to tap to allow for concurrent polling of reports

[agaman]

The long pole (pardon the pun) in this tap appears to be waiting for each account's reports to be generated by the Bing Ads API, and then polling for each of them one-at-a-time in serial.

This code change adds an event loop at the entry point of the tap in the main method and converts several underlying functions into coroutines.

There are two places in the code where concurrency is introduced. In do_sync_all_accounts and sync_reports the underlying tasks to sync account data and report data, respectively, are run concurrently and awaited.

Finally, in poll_report a call to time.sleep() has been replaced with an awaited call to asyncio.sleep(). This is where concurrency is actually introduced and where another task will be scheduled on the event loop if the report is not yet ready to download.

I have tested this code locally using my own developer key and my company's data, but would be glad to share the non-sensitive parts of my (admittedly brittle) integration tests.

This is my first PR for a Singer project and I'd love feedback about how I could make it better.

[cmerrick]

Hi @agaman, thanks for your contribution!

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[cmerrick]

You did it @agaman!

Thank you for signing the Singer Contribution License Agreement.

[KAllan357]

👍