adding switch for ForwardAgent in ssh_config (#818)

* Update openssh.conf.j2

add switch for FowardAgent

* Update openssh.conf.j2

fix typo

* Update openssh.conf.j2

change ssh_ForwardAgent to ssh_forward_agent

* Update argument_specs.yml

adding context for ssh_forward_agent

roles/ssh_hardening/templates/openssh.conf.j2

@@ -90,7 +90,9 @@ StrictHostKeyChecking ask
 
 {% endif %}
 # Disable agent forwarding, since local agent could be accessed through forwarded connection.
-ForwardAgent no
+
+ForwardAgent {{ ((ssh_forward_agent) if ssh_forward_agent is defined else 'no')}} 
+
 
 # Disable X11 forwarding, since local X11 display could be accessed through forwarded connection.
 ForwardX11 no