Publish "done" inline comment checkbox state in Diffusion

Summary:
Ref T1460. See D12126. This is essentially the same change, but for Diffusion.

This is a bit copy/pastey. I'm going to make an effort to lift inline handling into the core before pushing this in, so hopefully that will clean things up a bit.

Test Plan: Submitted stuff in Diffusion and got checkmarks to publish.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T1460

Differential Revision: https://secure.phabricator.com/D12128