Add cert-manager APIs as OLM dependencies

[eguzki]

In #727 the cert-manager APIs were removed as OLM dependencies. The reasons explained in the #727 description.

The RH build of the cert-manager is planning cluster wide scope feature. Tracked here: openshift/cert-manager-operator#188.

Once a release of RH cert-manager operator that supports cluster wide install mode is available, the main issue would be fixed and cert-manager APIs could be added back as OLM dependencies.

One test that needs to be done after bringing the cert-manager dependency back: verify that when the upstream operator is pre-installed, the RH build operator is not being installed in openshift.