Move remaining `paged-query-to-vec` logic into `query` namespace

This commit continues the refactor of the original `paged-query-to-vec`
implementation by removing the remaining bits into the `query`
namespace, along with the count logic that had already been moved
over.
Move `paging` namespace from `http` to `query`

It seems like more of the functionality that is encapsulated
by the new `paging` namespace relates to query-ish stuff than
to specifically http-ish stuff, so this commit just moves
it to the `query` namespace.