InlineEdit: Use Edit Message button for change edit workflow

Allow creating a change edit by changing the commit message with the
existing Edit message button. This way we still support the old
workflow, but we need one more click:

Old workflow:

* Click "Edit Message"
* Edit the message
* Click Save

Now it's one more click:

* Click "Publish Edit"

Change-Id: Ibe86995edde78097f10757e76b427818a1a30007
5 files changed