Handle shared secrets in operator

cc: @twk3

Part of https://gitlab.com/charts/gitlab/issues/753

This MR handles installation of the shared-secrets and migrations job in the operator.

Previously these were installed using helm from their specific charts and they were paused by helm so that the operator can take control from there.

In this MR the approach is changed. The operator expects to have access to configmaps that contains all the yaml manifests needed to install both jobs. Fetches the configmaps and exctracts the manifests and applies them using the api.

The installation/upgrade then proceeds if and only if both of the jobs succeeds or it keeps on retrying otherwise.

At that time helm will have unicorn and sidekiq deployments in a paused state until the operator proceeds after success of the jobs and unpauses them.