Attester controller shouldn't update spec

[cplee]

Whenever an attester CR is created without a secret, and the secret is then created by rode, the controller currently updates the spec of the CR setting the secret name. This should be replaced with a status value that contains the name of the secret that is being used to avoid mutating the spec provided in the original resource.

[gesparza3]

This issue was resolved by making pgbSecret a required field when creating Attester resources. See PR #29