Summary:
Ref T2222. This adds PHIDs to all Differential comments so I can migrate the inlinecommment table to transaction_comment in the next diff.
@wez, this will issue a few million queries for Facebook (roughly, one for each Differential comment ever made). It's safe to skip the `.php` half of the patch, bring Phabricator up normally, and then apply this patch with Phabricator running if that eases the migration, although the next few diffs will probably be downtime-required migrations so maybe it's easier to just schedule some downtime.
Test Plan: Ran migration locally. Verified existing comments and new comments received PHIDs.
Reviewers: btrahan
Reviewed By: btrahan
CC: wez, aran
Maniphest Tasks: T2222
Differential Revision: https://secure.phabricator.com/D6266
