Build separate comments for each inline comment in Audit

Summary:
Ref T4896. Moves us closer to migrating comments to transactions by building a transaction per inline.

This makes the UI a little wonky, and it will get slightly worse until we swap to the new UI and grouping/collapsing starts working. It's still usable, there's just a box per inline.

Test Plan:

• Added a comment.
• Added an inline comment.
• Added a comment and an inline comment.

Reviewers: btrahan, joshuaspence

Reviewed By: joshuaspence

Subscribers: epriestley

Maniphest Tasks: T4896

Differential Revision: https://secure.phabricator.com/D10023