Make operator chart handle disabled shared secrets properly

Ref: https://gitlab.com/charts/components/gitlab-operator/issues/32

Problem: helm chart has feature flags to not use shared secrets, but operator does not respect those

Solution:

• move flag shared-secrets.enabled -> global.sharedSecrets.enabled, pass it to operator
• add flag SharedSecretsTemplate.enabled to Gitlab operators Gitlab CRD
• don't try to create Job and RBAC objects to generate the secrets if shared secrets aren't enabled

Depends on changes in operator, see charts/components/gitlab-operator!28 (closed)

TODO:

• refactor conditions in shared-secrets charts to make them less complex
• handle deprecations properly

@twk3