Add SmartSurvey data to BigQuery

[nacnudus]

Currently, https://github.com/alphagov/govuk-feedback-processing/blob/main/src/services/smart_survey_service.py requests survey responses from the SmartSurvey API endpoint, and is scheduled to run daily. It is implemented as a Cloud Run Function, and handles its own retries and backoffs.

Options:

1. Scheduler -> Pub/Sub -> Function. Not so easy to handle backoff when backfilling several dates.
2. Scheduler -> Pub/Sub -> Workflow. This might get expensive, because the Workflow would charge per API request.
3. Scheduler -> Pub/Sub -> Workflow (to generate tasks) -> Tasks -> Function (triggered by http). Retries/backoff could be implemented in the task, rather than the function. Would the Workflow charge per task?
4. Scheduler -> Pub/Sub -> Function (to generate tasks) -> Tasks -> Function (triggered by https). Retries/backoff could be implemented in the task, rather than the function. Cheaper than Workflows.
5. Use Cloud Composer, which apparently has more sensible pricing now (isn't always on?)