ssh: Client HostKeyAlgorithms configuration variable (#442)

* ssh: Client HostKeyAlgorithms configuration variable

Introduce a new variable ssh_client_host_key_algorithms to be able to configure
it for the client like for the server.
This fixes #441

Signed-off-by: Paul Seidler <[email protected]>

* sshd: Adapt the ssh_host_key_algorithms description

Linking to the latest version may lead to a broken config so be a bit more
  dynamic

Signed-off-by: Paul Seidler <[email protected]>

roles/ssh_hardening/templates/openssh.conf.j2

@@ -81,6 +81,9 @@ StrictHostKeyChecking ask
 {# This outputs 'KexAlgorithms <list-of-algos>' if ssh_kex is defined or '#KexAlgorithms' if ssh_kex is undefined #}
 {{ 'KexAlgorithms ' ~ ssh_kex|join(',') if ssh_kex else 'KexAlgorithms'|comment }}
 
+# Specifies the host key algorithms that the client wants to use in order of preference.
+{{ "HostKeyAlgorithms " ~ ssh_client_host_key_algorithms|join(',') if ssh_client_host_key_algorithms else "HostKeyAlgorithms"|comment }}
+
 {% if sshd_version is version('5.9', '<') %}
 # Alternative setting, if OpenSSH version is below v5.9
 #MACs hmac-ripemd160