Most implement cursor paging in Maniphest

Summary:
Ref T2625. Depends on D6971. Maniphest is complicated to implement cursor paging for. Builds on D6971 to do so.

This is almost complete. Paging on projects and authors doesn't quite work, I'll clean that up shortly. Left some TODOs.

Test Plan: Set page size to 3, paged forward and backward in a bunch of group/order modes. Results seemed to be as expected.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2625

Differential Revision: https://secure.phabricator.com/D6972