Write the glue to include and use the in-context JavaScript in our EC workflow. Do this in a new form so that we can A/B test the integrations against one another.

This should eventually be enabled for the supported countries, but it's possible that enabling for all countries will be a better approach in the long term, because there is allegedly a transparent fallback from in-context to regular EC. It would be nice pick up additional in-context countries as they are allowed on the PP side, as long as we don't incur extra round-trips.