Port Repository "Symbols" to Manage/Panel UI

Summary: Ref T10748. Port this, add EditEngine support, add some type validation to the transaction.

Test Plan:

• Edited via EditEngine.
• Edited via Conduit.
• Viewed via Management UI.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10748

Differential Revision: https://secure.phabricator.com/D15808