Add warning to results page if proposed enrolment date and actual enrolment date differ

[jaredlockhart]

If the actual enrolment date and the proposed enrolment date differ by more than 2 days we should show a warning on the results page taht clearly indicates that only the proposed enrolment window was used to compute results, not the actual enrolment window (as controlled by teh end enrolment button), and if they want to include users outside of the proposed enrolment window in the analysis, they'll need to build a custom jetstream config which overrides the enrolment period dates.

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