Until now, when an owner/uploader replied, we always added all
of the reviewers to the attention set. We understand that added
too many users to the attention set.
With this change, we no longer add all reviewers to the attention
set when an owner/uploader replies.
On open changes, we now add all users that received a reply on
one of their comments.
On closed changes, we no longer add the owner and uploader when
reviewers reply. We do add the owner if there is a new comment
thread on the change (inReplyTo = null).
Also, we now ensure that users that are not owner, uploader, reviewer
or CC can't be added to the attention set this way.
Change-Id: Idcf0692d1f53e13d07b27d96de4ffb4120e2f59c
ddb437b0de