Clean up some Ponder language

Summary:
Ref T9099.

• Remove unused function
• Fix celerity resource include
• Add a note when an answer's been closed
• Clean up architecture a little
• Add a better notice when you've already answered.

Test Plan: Test with and without answers, with answering, with being closed.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9099

Differential Revision: https://secure.phabricator.com/D13875