feat: add SMTP submission listener and enhance stalwart configuration (#425)

- add SMTP submission listener on port 587 with TLS requirement
- configure HAProxy frontend/backend for submission with send-proxy-v2 support
- add send-proxy-v2 support to all listeners
- add dynamic HAProxy node discovery for proxy trusted networks
- use service hostname instead of node FQDN for autoconfig/autodiscover
- remove redundant IMAP/IMAPS/SMTP alt-names from TLS certificates
- update VRRP CNAME configuration to use mail.main.unkin.net

Reviewed-on: #425

modules/stalwart/manifests/config.pp

@@ -29,6 +29,7 @@ class stalwart::config {
     content => epp('stalwart/config.toml.epp', {
       'cluster_size'            => $stalwart::cluster_size,
       'other_cluster_members'   => $stalwart::other_cluster_members,
+      'haproxy_ips'             => $stalwart::haproxy_ips,
       'effective_node_id'       => $stalwart::effective_node_id,
       'bind_address'            => $stalwart::bind_address,
       'advertise_address'       => $stalwart::advertise_address,
@@ -49,10 +50,12 @@ class stalwart::config {
       'enable_imap'             => $stalwart::enable_imap,
       'enable_imap_tls'         => $stalwart::enable_imap_tls,
       'enable_http'             => $stalwart::enable_http,
+      'enable_smtp_submission'  => $stalwart::enable_smtp_submission,
       'data_dir'                => $stalwart::data_dir,
       'tls_cert'                => $stalwart::tls_cert,
       'tls_key'                 => $stalwart::tls_key,
       'log_level'               => $stalwart::log_level,
+      'service_hostname'        => $stalwart::service_hostname,
       'fallback_admin_user'     => $stalwart::fallback_admin_user,
       'fallback_admin_password' => $stalwart::fallback_admin_password,
       'webadmin_unpack_path'    => $stalwart::webadmin_unpack_path,