Refactor byChange() into two methods: drafts and published

Callers of the PatchLineCommentUtils.byChange() mostly just want
either the published comments or the drafts comments. For that reason,
I refactored this method into two pieces and updated its callers.

I modified ChangeData.comments() to be ChangeData.publishedComments()
in order to more accurately the contents of the returned list.

Change-Id: I4222b894896af1ae635fd8c390fe014db9f6778d
5 files changed