Improve upon OONI Run

[hellais]

This epic tracks improvements to the OONI Run platform based on community feedback shared as part of our OONI Run Usability Study: https://ooni.org/post/2020-06-09-ooni-run-usability-study-findings/

[agrabeli]

Feature requests:

• Ability to save a list of URLs and to be able to go back to it to add and remove URLs to generate new OONI Run links => We could save this in a general OONI account.

• Ability to save previously generated OONI Run links (and re-run them) => We would save this in the OONI Probe mobile app so that they can re-test OONI Run links through the app.

[agrabeli]

More community feedback for improving OONI Run: ooni/run#70

[hellais]

Document with the user feedback for the OONI Run: https://docs.google.com/document/d/1ayM-aUyIdwgTEd-m14f1y8zkHKbtOeRWEEziI0AHi9E/edit