refactor: add new setting core.relayPort to override core.port for reverse proxies. core.port will be used by plugins, but core.relayPort may be used by core

src/config.ts

@@ -26,6 +26,7 @@ switch (os.platform()) {
 config.inject({
   "core.confDir": configDir,
   "core.port": 8080,
+  "core.relayPort": 0,
   "core.appPort": 80,
   "core.logLevel": "info",
   "core.pluginDir": path.resolve(configDir, "..", "plugins"),

src/modules/relay.ts

@@ -29,5 +29,11 @@ export async function start() {
     relay(dht, new Stream(false, connection.socket));
   });
 
-  await relayServer.listen({ port: config.uint("core.port"), host: "0.0.0.0" });
+  let port = config.uint("core.relayPort");
+
+  if (!port) {
+    port = config.uint("core.port");
+  }
+
+  await relayServer.listen({ port, host: "0.0.0.0" });
 }