[YiR] Clear out edit data upon logout, populate data upon login and settings toggle

[tonisevener]

Phabricator: https://phabricator.wikimedia.org/T378135

Notes

This PR clears out the user's YiR editing data upon logout, so that if they log in with a different username they will not see the old edit count slide.

I also did some cleanup with data population, so that we don't have to background / foreground as often. I am now also populating data upon login and whenever the YiR settings toggle is turned on.

Test Steps

1. Log into an account with editing data. Confirm you see account reflected in Year in Review.
2. Log out.
3. Log into another account with a different edit count. Confirm you see new count in Year in Review.
4. Go to app Settings, turn off year in review. Confirm entry point disappears. Go back to settings and turn year in review back on. Confirm entry point comes back without needing to background/foreground.