[Chore] App secret names should be valid uuids

[danail-branekov]

When an app is being reconciled, the app controller creates vcap-application and vcap-services secrets whose names are set to app_name, followed by the -vcap-services and -vcap-application suffixes. This naming convention is quite naive, names should really be uuids. Furthermore, the secret names are stored in the app status, so using naming convention does not really make sense.

Action to take

• The app controller should set uuid.NewString() (uuidv4) names for those secrets
• Make sure that such a change does not affect existing apps. It shouldn't as the secret names should be already stored in the app status