Rename setMembers() to withMemberPHIDs() in PhabricatorProjectQuery

Summary: This is clearer and more consistent with other Query classes.

Test Plan: Used home page, conduit api, project list, other interfaces.

Reviewers: vrana, btrahan

Reviewed By: vrana

CC: aran

Maniphest Tasks: T603

Differential Revision: https://secure.phabricator.com/D3179