Fix some of the most obvious bugs in fact generation from Maniphest tasks

Summary:
Depends on D19121. Ref T13083. Group transactions and show groups in the debugging view.

Fix some of the most obvious issues with fact generation:

• No more 0-point facts.
• Engine can now generate at least one of every type of fact.

Test Plan: Generated facts, viewed them in the debugging view, fact generation largely appeared to align with reality. No more "no facts in storage" facts.

Subscribers: yelirekim

Maniphest Tasks: T13083

Differential Revision: https://secure.phabricator.com/D19122