Make client inlines track an "active" state

Summary:
Ref T13559. Rather than reading from the document, make client inlines actively track their current "active" state.

The "active" state is what the user currently sees in the client UI.

Test Plan: Created inlines, etc. See followups.

Maniphest Tasks: T13559

Differential Revision: https://secure.phabricator.com/D21646