Fix keystone fernet file exchange via ssh

* install openssh client in keystone-fernet container
* install rsync in keystone-ssh container
* fix syntax issue in ssh configuration
* copy ssh configuration into keystone-fernet container
* copy id_rsa.pub into keystone-ssh container
* copy id_rsa into keystone-fernet container
* use full path to ssh binary in used scripts
* add missing newlines at EOF
* when using type source set /var/lib/keystone as home
  directory for the user keystone

Co-Authored-By: Jeffrey Zhang <jeffrey.zhang@99cloud.net>
Change-Id: Id6b41030056a69f6516a054beb2fc0e08226e876
Closes-bug: #1623013