Cancel requests when scrolling past a section

[garrettjstevens]

If we scroll past an area before it finishes fetching the data, we should cancel the fetch so that it doesn't fetch unnecessary data.

[shashankbrgowda]

In order to reduce the response size of /features/getFeatures?refSeq=&start=&end= endpoint, can we fetch only necessary fields and skip fields like alIds, attributes etc. when we fetch features for rendering in apollo track ?