puppet: Create zmirror supervisor subdirectory.

To not change the `supervisor.conf` file, which requires a restart of
supervisor (and thus all services running under it, which is extremely
disruptive) we carefully leave the contents unchanged for most
installs, and append a new piece to the file, only for the zmirror
configuration, using `concat`.

puppet/zulip/manifests/supervisor.pp

@@ -97,15 +97,24 @@ class zulip::supervisor {
     }
   }
 
-  file { $zulip::common::supervisor_conf_file:
-    ensure  => file,
+  concat { $zulip::common::supervisor_conf_file:
+    ensure  => 'present',
     require => Package[supervisor],
     owner   => 'root',
     group   => 'root',
     mode    => '0644',
-    content => template('zulip/supervisor/supervisord.conf.erb'),
     notify  => Exec['supervisor-restart'],
   }
+  concat::fragment { '00-supervisor-top':
+    order   => '01',
+    target  => $zulip::common::supervisor_conf_file,
+    content => rstrip(template('zulip/supervisor/supervisord.conf.erb')),
+  }
+  concat::fragment { '99-supervisor-end':
+    order   => '99',
+    target  => $zulip::common::supervisor_conf_file,
+    content => "\n",
+  }
 
   file { '/usr/local/bin/secret-env-wrapper':
     ensure => file,

puppet/zulip_ops/manifests/profile/zmirror_personals.pp

@@ -27,8 +27,14 @@ class zulip_ops::profile::zmirror_personals {
     source => 'puppet:///modules/zulip_ops/krb5.conf',
   }
 
+  concat::fragment { '01-supervisor-zmirror':
+    order   => '10',
+    target  => $zulip::common::supervisor_conf_file,
+    content => " ${zulip::common::supervisor_system_conf_dir}/zmirror/*.conf",
+  }
+
   file { ['/home/zulip/api-keys', '/home/zulip/zephyr_sessions', '/home/zulip/ccache',
-          '/home/zulip/mirror_status']:
+          '/home/zulip/mirror_status', "${zulip::common::supervisor_system_conf_dir}/zmirror"]:
     ensure => directory,
     mode   => '0755',
     owner  => 'zulip',