Add final/destination URL field to LighthouseRun object

[ecumike]

The scenario is that a URL might be submitted for tracking, but is actually not the final destination URL (AKA; it's a redirect).

Other case is that a page might get moved or sunset and redirected to a new URL.

Storing the "final" URL for each LighthouseRun allows the insights to see that if there was a drastic change in performance or URL audit metrics, it may be because a different page is actually being tested for that URL than previous runs.

This is minimal effort and is data already provided in Lighthouse report data.
Add a field to LighthouseRun obj.
In the method where we process posted LighthouseRawdata, like we do other bits, grab the URL from the data object and add it to the LHrun record.

A follow-on UI piece will be covered in a separate issue.