api: automatically pull youtube session tokens from a session server

if provided, cobalt will pull poToken & visitor_data from an instance of invidious' youtube-trusted-session-generator or its counterpart

api/src/core/api.js

@@ -18,8 +18,10 @@ import { verifyTurnstileToken } from "../security/turnstile.js";
 import { friendlyServiceName } from "../processing/service-alias.js";
 import { verifyStream, getInternalStream } from "../stream/manage.js";
 import { createResponse, normalizeRequest, getIP } from "../processing/request.js";
+
 import * as APIKeys from "../security/api-keys.js";
 import * as Cookies from "../processing/cookie/manager.js";
+import * as YouTubeSession from "../processing/helpers/youtube-session.js";
 
 const git = {
     branch: await getBranch(),
@@ -376,6 +378,10 @@ export const runAPI = async (express, app, __dirname, isPrimary = true) => {
         if (env.cookiePath) {
             Cookies.setup(env.cookiePath);
         }
+
+        if (env.ytSessionServer) {
+            YouTubeSession.setup();
+        }
     });
 
     if (isCluster) {