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