Formally modularize MFA/TOTP tokens, provide a module panel for temporary tokens

Summary:
Ref T10603. We have a couple of sort of ad-hoc tokens, so start formalizing them. First up is MFA tokens.

Also adds a new config module panel for these.

Test Plan:

• Added MFA.
• Added MFA, intentionally fumbled the input, completed the workflow.
• Removed MFA.
• Viewed tokens, saw MFA sync tokens.
• Viewed new module config panel.

{F1177014}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10603

Differential Revision: https://secure.phabricator.com/D15479