Rename "getReviewerStatus()" to "getReviewers()"

Summary:
Ref T10967. Improves some method names:

• Revision->getReviewerStatus() -> Revision->getReviewers()
• Revision->attachReviewerStatus() -> Revision->attachReviewers()
• Reviewer->getStatus() -> Reviewer->getReviewerStatus() (this is mostly to make this more greppable)

Test Plan:

• bunch o' grep
• Browsed around.
• If I missed anything, it should fatal in an obvious way. We have a lot of other getStatus() calls and it's hard to be sure I got them all.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10967

Differential Revision: https://secure.phabricator.com/D17522