Decide and implement the prefetching strategy for new posts

[Poliuk]

The prefetching affects different parts of the app:

• Load more button at the end of the post-list
• Swipe right/left to read next article / infinite scrolling (https://github.com/worona/saturn-app-theme-worona/issues/19 - https://github.com/worona/saturn-app-theme-worona/issues/11 )
• Swipe right/left to see next category post-list