Add environment variables for assisted digital survey to feedback
Add environment variables for assisted digital survey to feedback

These will hold the key of the spreadsheet to write survey results to and
the email and private key credentials of the service account to use to
perform the write.  Each environment will have their own values for this
and it'll come from the encrypted puppet hieradata.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet