Add more oslo::cache params to init

Add more oslo::cache params to init

This adds two new parameters cache_backend
and manage_backend_package that is simply
proxy parameters that is passed down to
oslo::cache like all other modules.

This does not introduce a behavior change
since cache_backend defaults to
$::os_service_default we do not enforce
any new package installs even though
manage_backend_package is set to true
(like it was before since that is
oslo::cache default)

Updates the testing so we test for the
oslo::cache resource and not the functionality
that the resource itself has.

Change-Id: Ib6f6853dd34e83e757bee0382ee84141e3f4dbd8