fix(flags): Init flags before creating XMPP conn.

This allows us to set defaults through jitsi-meet. Also remove undocumented setting enableJoinAsVisitor that is no longer needed.

JitsiConnection.js

 import JitsiConference from './JitsiConference';
 import * as JitsiConnectionEvents from './JitsiConnectionEvents';
+import FeatureFlags from './modules/flags/FeatureFlags';
 import Statistics from './modules/statistics/statistics';
 import XMPP from './modules/xmpp/xmpp';
 import {
     this.appID = appID;
     this.token = token;
     this.options = options;
+
+    // Initialize the feature flags so that they are advertised through the disco-info.
+    FeatureFlags.init(options.flags || {});
+
     this.xmpp = new XMPP(options, token);
 
     /* eslint-disable max-params */

JitsiMeetJS.ts

 
         Settings.init(options.externalStorage);
         Statistics.init(options);
-        const flags = options.flags || {};
-
-        // Configure the feature flags.
-        FeatureFlags.init(flags);
 
         // Initialize global window.connectionTimes
         // FIXME do not use 'window'

modules/flags/FeatureFlags.js

      * @param {object} flags - The feature flags.
      * @param {boolean=} flags.runInLiteMode - Enables lite mode for testing to disable media decoding.
      * @param {boolean=} flags.ssrcRewritingEnabled - Use SSRC rewriting.
-     * @param {boolean=} flags.enableJoinAsVisitor - Enable joining as a visitor.
      */
     init(flags) {
         this._runInLiteMode = Boolean(flags.runInLiteMode);
         this._ssrcRewriting = Boolean(flags.ssrcRewritingEnabled);
-        this._joinAsVisitor = Boolean(flags.enableJoinAsVisitor ?? true);
     }
 
     /**
     isSsrcRewritingSupported() {
         return this._ssrcRewriting;
     }
-
-    /**
-     * Checks if the clients supports joining as a visitor.
-     * @returns {boolean}
-     */
-    isJoinAsVisitorSupported() {
-        return this._joinAsVisitor;
-    }
 }
 
 export default new FeatureFlags();

modules/xmpp/moderator.js

 import { $iq } from 'strophe.js';
 
 import { CONNECTION_REDIRECTED } from '../../JitsiConnectionEvents';
-import FeatureFlags from '../flags/FeatureFlags';
 import Settings from '../settings/Settings';
 import Listenable from '../util/Listenable';
 
             conferenceRequest.sessionId = sessionId;
         }
 
-        if (FeatureFlags.isJoinAsVisitorSupported() && !config.iAmRecorder && !config.iAmSipGateway) {
+        if (!config.iAmRecorder && !config.iAmSipGateway) {
             conferenceRequest.properties['visitors-version'] = 1;
 
             if (this.options.preferVisitor) {

modules/xmpp/xmpp.js

         // the version added in moderator.js, this one here is mostly defined
         // for keeping stats, since it is not made available to jocofo at
         // the time of the initial conference-request.
-        if (FeatureFlags.isJoinAsVisitorSupported()) {
-            this.caps.addFeature('http://jitsi.org/visitors-1');
-        }
+        this.caps.addFeature('http://jitsi.org/visitors-1');
     }
 
     /**