fix: Load More pagination based on ES7 hit counts

[anandaroop]

775 fixed a display issue that resulted from the change in hits.total's shape starting with ES7

Turns out there was a more substantive issue too — Load More pagination was broken, and needed to be taught about the new shape.

I also made the UI handle the case where have more than 10K results (indicated in the response by { hits: { total: { value: 10000, relation: "gte" } } }