Remove direct reads of form state from main Inline client code

Summary:
Ref T13559. Instead of directly reading form state, make all callers use the "active" state instead. The state reads the form.

No functional changes, just clarifying responsiblites.

Test Plan: Created inlines, etc. See followup changes.

Maniphest Tasks: T13559

Differential Revision: https://secure.phabricator.com/D21647