write ciphers,macs and kex as comma-separated string

[ReneTrippen]

As the man page of sshd_config(5) describes:
"Multiple ciphers/macs/kexalgorithms must be comma-separated." Using an array or YAML list for ciphers/mac/kex results in multiple entries in sshd_config. If multiple entries are set in sshd_config, sshd takes only the first one.

Fixes #361

With this fix, we can write the server_options for ciphers/macs/kexalgorithms as an array or as yaml list in hiera, that increases the readability a lot :)
@bastelfreak @SimonHoenscheid could you please take a look?

Example

class { 'ssh':
  storeconfigs_enabled => false,
  server_options => {
    'Ciphers'       => [ 'aes128-ctr', 'aes192-ctr', 'aes256-ctr', 'aes128-cbc', '3des-cbc', 'aes192-cbc', 'aes256-cbc' ],
    'Macs'          => [ 'hmac-sha2-512-etm@openssh.com', 'hmac-sha2-256-etm@openssh.com', 'hmac-sha2-512', 'hmac-sha2-256' ],
    'KexAlgorithms' => [ 'curve25519-sha256', 'curve25519-sha256@libssh.org', 'diffie-hellman-group14-sha256', 'diffie-hellman-group16-sha512' ],
  },
}

generated sshd_config

# File is managed by Puppet

AcceptEnv LANG LC_*
ChallengeResponseAuthentication no
Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc
KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512
Macs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
PrintMotd no
Subsystem sftp /usr/libexec/openssh/sftp-server
UsePAM yes
X11Forwarding yes

sshd -T

sshd -T | grep -E "(^cipher|^kexal|^mac)"
ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,aes192-cbc,aes256-cbc
macs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
kexalgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group14-sha256,diffie-hellman-group16-sha512

[ReneTrippen]

looks like the centos 8 container with puppet 8 was running into a timeout while spinning up

[ReneTrippen]

@saz can we restart the check pipeline?

[bastelfreak]

@ReneTrippen you can close and reopen the PR, that will restart the pipeline.