R1:8449c1793ace

Convert complex query subclasses to use internal cursors

Summary:
Depends on D20292. Ref T13259. This converts the rest of the `getPagingValueMap()` callsites to operate on internal cursors instead.

These are pretty one-off for the most part, so I'll annotate them inline.

Test Plan:
- Grouped tasks by project, sorted by title, paged through them, saw consistent outcomes.
- Queried edges with "edge.search", paged through them using the "after" cursor.
- Poked around the other stuff without catching…