Add "Committer's projects" and "Author's projects" fields to Herald commit rules

Summary:
Ref T13093. See PHI396. These are possibly somewhat niche, but reasonable to support and consistent with the existing "Pusher's projects".

Also relabel "Pusher's projects" and "Project tags" for consistency and, hopefully, clarity.

Test Plan:

• Created new "commit" and "hook: commit content" Herald rules which run against "Author's projects" and "Committer's projects".
• Test console'd the "Commit" rules.
• Pushed through the "Hook" rule.
• In all cases, saw fields populate appropriately.

Maniphest Tasks: T13093

Differential Revision: https://secure.phabricator.com/D19145