R1:a115810912e7

Give projects a proper on-demand datasource

Summary:
Fixes T5614. Ref T4420. Other than the "users" datasource and a couple of others, many datasources ignore what the user typed and just return all results, then rely on the client to filter them.

This works fine for rarely used ("legalpad documents") or always small ("task priorities", "applications") datasets, but is something we should graudally move away from as datasets get larger.

Add a token table to projects, populate it, and use it to drive the…