Story

As a user of cluster log forwardering to a "fluent forward" output,
I need to configure the passphrase for my TLS client private key
so auth is configured properly to allow communication to the destination

Acceptance Criteria

• CLF with forward output sends records to "forward " service configured to use certs where the private key is protected with a pass phrase
• The generated configuration uses the parameter "tls_client_private_key_passphrase" for the configured output
• Documented secret key that is recognized by ClusterLogForwarder
• Unit test verifying the new configuration

Notes

• Possible secret key values: passphrase, privateKeyPassphrase, ?
• This change only applies to forward outputs but we should consider its applications to others
• There is another story that is intended to over haul authorization configuration