Add code to deploy rbac proxy

[misohu]

Fixes https://github.com/canonical/pvcviewer-operator/issues/14

The charm was missing kube-rbac-proxy image with setup.

Changes:

• deploy kube-rbac-proxy
• rbac-proxy image is correctly set
• add service for kube-rbac-proxy (same service as operator just another port)
• add tests

[misohu]

The publish script will fail as I introduced new image which I need to first upload manually to charmhub ... I will do it after this PR is approved