This commit adds capability to `metadata` encryption
to be able to fetch `encryptionPassphrase` from user
specified secret name and namespace(if not specified,
will default to namespace where PVC was created).
This behavior is followed if `secretName` key is found
in the encryption configuration else defaults to fetching
`encryptionPassphrase` from storageclass secrets.
Closes: 2107
Signed-off-by: Rakshith R <rar@redhat.com>