Add CMake templates to build/publish DEB/RPM pkgs

Add CMake templates to build/publish DEB/RPM pkgs

New templates gerrit-cmake-packagecloud-stage and
github-cmake-packagecloud-stage for building DEB/RPM package
files and publishing them to a PackageCloud.io repository on
posted comment.  Adds builder macros lf-packagecloud-file-provider
and lf-packagecloud-push.  Adds script packagecloud-push.sh to
call Ruby gem package_cloud.
The new templates are lifted from the ORAN project.

Change-Id: Ia39f5b43c2ef22485166a5f54fcf31d53eab84f8
Issue-ID: RELENG-2832
Signed-off-by: Lott, Christopher (cl778h) <cl778h@att.com>