Mirror the GitHub reporter's "comment" option to allow for supressing
review messages when reporting to Gerrit. This is needed for use with
the checks api since the purpose is to avoid leaving job results in
comments. This removes the ability for 'comment' to be a review label,
which seems unlikely, but plausible, so a release note is added.
Rename the "checks_api" Gerrit reporter option to "checks-api" for
hyphen consistency with the rest of the configuration. This is an
experimental feature and not generally useful yet, so no release note
is included. This change supports both forms and updates the
documentation; a later change will remove "checks_api".
While adding documentation for the "comment" option, the description
of the Gerrit reporter is updated.
A small refactoring of the Gerrit reporter is undertaken to make
dealing with additional non-label options easier.
Change-Id: I44c0ba93601f3be3eb0f094bd782cecc4a0372f7
c6db86ad38