Fixed visibility parameter for create package glare call
Fixed visibility parameter for create package glare call

When creating a murano-package artifact in Glare muranoclient was not
properly passing the visibility parameter. Instead, it was passing the
'is_public' parameter, which is not supported by Glare.

Appropriate conversion has been added to PackageManagerAdapter class

Change-Id: Ia3a038d2b16e27effd208f5e4877f1f06d8ad882
Closes-bug: #1537018

openstack/python-muranoclient,openstack/python-muranoclient