We need to create an Explore data controller in WMFData that is responsible for returning Explore data back to the UI layer. For now this data controller needs to:

1. Add a public method to fetch Explore feed "Community Picks" data. Internally call the feed data controller (T413380)'s fetchData.
2. Add a public method to fetch previous page of Explore feed data. This data controller must keep track of dates that were already fetched. Then this method for paging will fetch and return the previous date of data.

Note: there's no need to call this work from our existing Explore feed UI. We will use them only once we rewrite the UI layer.