Fix pagination state for `coins` and `blocks` query

[luizstacio]

When navigating to first or last pages, where the page size is even, the pagination state is computing wrongly. We have fixed pagination on transactions on #323. But we also need to implement it on other pagination queries like coins and blocks.

scenario

In a scenario where the iterable list is; [1,2,3,4,5,6,8,9]

Page 1; transactions(first: 3) -> should return hasPreviousPage: false and hasNextPage: true.

Page 2; transactions(first: 3, after: <Page1.endCursor>) -> should return hasPreviousPage: true and hasNextPage: true.

Page 2; transactions(first: 3, after: <Page2.endCursor>) -> should return hasPreviousPage: true and hasNextPage: false.