syslog: change it to unix domain socket

docker is using a extra udp port for every container. when there is
a lot of containers, a lot of random udp ports get used up. this causes
problems when installing apps that require contiguous port ranges

src/paths.js

@@ -68,5 +68,7 @@ exports = module.exports = {
     BACKUP_LOG_FILE: path.join(baseDir(), 'platformdata/logs/backup/app.log'),
     UPDATER_LOG_FILE: path.join(baseDir(), 'platformdata/logs/updater/app.log'),
 
+    SYSLOG_SOCKET_FILE: path.join(baseDir(), 'platformdata/logs/syslog.sock'),
+
     OIDC_STORE_DIR: path.join(baseDir(), 'platformdata/oidc'),
 };