Extend GSSAPI configuration support to ssh_config

Previously, the ssh_gssapi_support variable only toggled the GSSAPI
settings in sshd_config.

Through this change, setting ssh_gssapi_support to true also enables
support in ssh_config.

It enables both authentication and credential delegation.

roles/ssh_hardening/templates/openssh.conf.j2

@@ -104,8 +104,8 @@ RSAAuthentication yes
 PasswordAuthentication {{ 'yes' if ssh_client_password_login else 'no' }}
 
 # Only use GSSAPIAuthentication if implemented on the network.
-GSSAPIAuthentication no
-GSSAPIDelegateCredentials no
+GSSAPIAuthentication {{ 'yes' if ssh_gssapi_support else 'no' }}
+GSSAPIDelegateCredentials {{ 'yes' if ssh_gssapi_support else 'no' }}
 
 # Disable tunneling
 Tunnel no