Add a successive_visits counter to origin visit stats
This maintains the number of successive visits resulting in the same status. This will help implementing disabling of too many successive failed or not_found visits for a given origin [1]
Related to #2345 Depends on !325 (closed)
- [1] D5980
Supersedes !190 (closed) (which I plan to commandeer and close)
Test Plan
tox
Migrated from D5978 (view on Phabricator)