Add required needMembers/needWatchers calls to Project Profile/Subprojects tabs

Summary:
Fixes T12710. See that task for discussion. This is pretty ugly/redundant but not broken.

(Feel free to reject this and pursue something else.)

Test Plan:

• For a project with active subprojects/milestones, viewed the project profile and subprojects tabs.
• After patch: they're ugly, but no longer fatal.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12710

Differential Revision: https://secure.phabricator.com/D17882