refs https://github.com/TryGhost/Ghost/issues/7860
- remove preview pane from content screen
- add basic post status filters
- replace custom infinite scroll with ember-infinity and increase trigger threshold for improved scroll behaviour
Commits:
* basic content list + filter using existing infinite scroll and pagination
* swap our custom pagination + infinite loader for `ember-infinity`
* minor cleanups
* reset scroll position when changing filter
* fix tests
* remove client-side sorting step as we no longer have a live collection
* remove unused `mobile-index-route`
* add acceptance tests for content screen filters
* chore(package): update ember-one-way-controls to version 2.0.0
* update yarn.lock
* update `gh-trim-focus-input` for removal of `sanitizeInput` in `ember-one-way-controls`