Make JX.Aphlict a real singleton with a more sensible initialization order

Summary:
Ref T5373. The control flow between aphlict-listener and JX.Aphlict is pretty weird right now, where the listener (which is the highest-level component) has intimate knowledge of how to put the SWF on the page.

Instead:

• Make JX.Aphlict a real singleton.
• Instantiate it sooner.
• Have it handle the flash setup handshake.

Test Plan: Loaded page in debug mode, saw normal flow take place.

Reviewers: joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Maniphest Tasks: T5373

Differential Revision: https://secure.phabricator.com/D9699