Set a default timeout parameter for BigQuery queries.

Detailed Description

Per Google BQ query job documentation, it's possible to pass a default timeout parameter to the synchronous call that awaits a response.

This change would require choosing a reasonable maximum default (30s?), setting that up as a configurable parameter, and passing that parameter into load_job.result.

Context

Generally, it's best practice to establish a timeout for database connections, to prevent code from indefinitely waiting for a response under unreliable network conditions.

Per #452, there was existing low-priority work to set this up with the built-in SQL connector. Having a well-chosen default timeout and good notifications around errors will make everything dependent on parsons more robust.

Possible Implementation

Should be as easy as changing

and

to load_job.result(timeout=MAX_TIMEOUT)

Priority

High -- this is a very low lift now, but becomes much harder to implement and test once more code becomes dependent on the new BQ connector.