VE-1528: Infinite scroll for suggestions

https://wikia-inc.atlassian.net/browse/VE-1528
I did consider it and first looked to see how it had been resued in the WikiaMapInsertDialog. It seemed like a bit of a red flag that the 'preview' event was being used to trigger 'onMapSelect'. I also looked at how WMF is doing it in their MWMediaInsertDialog and found that it's very tied to a search experience. A longer-term solution would probably be to create a mixin that handles firing an event when the bottom of a scrollable layout is nearly reached.