Show all packages with a claim on a file in the table of contents view

Summary:
Ref T9218. See discussion there for rationale; I think this is the right behavior to pursue.

The screenshot below is pretty ugly. I think it's a lot worse than most real-world cases will be, since you have to sort of opt-in to having crazy levels of overlapping packages, and it's perfectly normal/reasonable for files owned by one package. Owners is powerful enough to let you specify sub-packages with exclusive ownership.

That said, this may be more typical than I hope. I don't think we can reduce the complexity here much for free, but it would might be reasonable to add some view options (e.g.: group by package?, show only packages I own?, show packages as icons with a tooltip?) if it's an issue.

Test Plan:

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9218

Differential Revision: https://secure.phabricator.com/D13940