Revamp inline commenting UI

Summary:
Rebuilds the UI in Differential commenting. Specifically we look at the following design patterns:

To the author:

• The author of the diff should be able to easily identify what comments are done and not done.
• We keep undone comments yellow
• Clicking done turns comment block into 'unsubmitted state'

To the reviewer:

• Easier understanding of unsubmitted states
• All conversations to be yellow/important

Todo

• Not all color CSS states correct
• Unpulished checkbox support

Test Plan:
Test leaving comments, published and unpublished. Checking Done, unpublished and published. Check delete states.

From the Diff Author's perspective:

For a Diff commenter's perspective:

Reviewers: btrahan, epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T1460, T7660, T7503

Differential Revision: https://secure.phabricator.com/D12171