…lipped CV layouts

UICollectionViewLayout has a property called `flipsHorizontallyInOppositeLayoutDirection`. If this is set to `YES` then a RTL collectionView’s contentOffset behaves like it does in LTR. In other words, the first item is at contentOffset 0. In this case, the existing logic for `ASDisplayShouldFetchBatchForScrollView` works in RTL.

If you don’t override `flipsHorizontallyInOppositeLayoutDirection` to be `YES`, then it means that in RTL languages the first item in your collectionView will actually be at x offset `collectionView.contentSize.width - collectionView.frame.size.width`. As you scroll to the right, the content offset will decrease until you reach the end of the data at a content offset of 0,0. In this case, `ASDisplayShouldFetchBatchForScrollView` needs to know that you are in RTL and the layout is not flipped. It can then use the contentOffset as the `remainingDistance` to determine when to fetch.