Add a new survey for DfE user research
Add a new survey for DfE user research

A 1 in 6 survey that runs across a bunch of DfE pages.  Like the HMRC
survey in the previous commit each page needs to have a different
`utm_campaign` value for the survey url so we use the same trick with a
mapping function that we reuse in `activeWhen`.

See: https://trello.com/c/nHar0yr3/191-govuk-survey-user-research-panel-invite-dfe

alphagov/static,alphagov/static,alphagov/static