Copy pod_environment_secret to the cluster namespaces

[dmvolod]

Fixes #1272

[FxKu]

The original author of this feature restricted it to the namespace for a reason. Not sure how I should feel about copying a secret with credentials around. @frittentheke fyi.

[dmvolod]

The original author of this feature restricted it to the namespace for a #946 (comment).

Yes, I know, it's a Kubernetes limitations and couldn't be be broken.

Not sure how I should feel about copying a secret with credentials around.

Yes, totally agree with you, for some reasons security restrictions could be occured. But we could introduce an option inside the OperatorConfiguration to copy/not copy secretes form the single location to avoid creation them on every namespace where Postgresql has deployed. Also allowing to configure configmap/secret for each CR (#1794) is more preferred option.