Finish issues found in [[ https://github.com/wikimedia/wikipedia-ios/pull/3677 | deep link PR ]]. Original PR was merged to get in for Apple beta.
1. Test to see if deep link could potentially pull in a non-EN Wikipedia content group, if that happens to be the latest. If so, adjust content group fetching to only pull EN, since that's the only deep link we're targeting so far.
2. Layout issues - Deep link header ignores safe area on the left side
3. Layout issues - There's a large space when rotating (try `updateScrollViewInsets`)
4. Nav bar title shows when the view appears. We don't want a title showing on launch if the header is visible.
5. When re-creating the stack, On This Day VC is hydrated as a "from the explore feed VC" (with an X button and no nav bar) rather then the version that should be in the stack. (To replicate: Open app, open On This Day via deep link, background the app, then hard quit and re-run the app.)