R1:fa2d30ee3698

Lift inline comment draft behaviors to "InlineController"

Summary:
Ref T13513. Currently, if you:

- click a line to create an inline;
- type some text;
- wait a moment; and
- close the page.

...you don't get an "Unsubmitted Draft" marker in the revision list.

Lift all the draft behavior to "InlineController" and make saving a draft dirty the overall container draft state.

Test Plan:
- Took the steps described above, got a draft state marker.
- Created, edited, submitted, etc., inlines in…