feat(MobileDeepLinking): Enable custom deeplinking domain

interface_config.js

      */
     // MOBILE_DOWNLOAD_LINK_IOS: 'https://itunes.apple.com/us/app/jitsi-meet/id1165103905',
 
+    /**
+     * Specify Firebase dynamic link properties for the mobile apps.
+     */
+    // MOBILE_DYNAMIC_LINK: {
+    //    APN: 'org.jitsi.meet',
+    //    APP_CODE: 'w2atb',
+    //    CUSTOM_DOMAIN: undefined,
+    //    IBI: 'com.atlassian.JitsiMeet.ios',
+    //    ISI: '1165103905'
+    // },
+
     /**
      * Specify mobile app scheme for opening the app from the mobile browser.
      */

react/features/deep-linking/components/DeepLinkingMobilePage.web.js

     _generateDownloadURL() {
         const url = _URLS[Platform.OS];
 
-        if (url) {
+        if (url && typeof interfaceConfig.MOBILE_DYNAMIC_LINK === 'undefined') {
             return url;
         }
 
         const {
             APN = 'org.jitsi.meet',
             APP_CODE = 'w2atb',
+            CUSTOM_DOMAIN = undefined,
             IBI = 'com.atlassian.JitsiMeet.ios',
             ISI = '1165103905'
         } = interfaceConfig.MOBILE_DYNAMIC_LINK || {};
+
+        const domain = CUSTOM_DOMAIN ?? `https://${APP_CODE}.app.goo.gl`;
         const IUS = interfaceConfig.APP_SCHEME || 'org.jitsi.meet';
 
-        return `https://${APP_CODE}.app.goo.gl/?link=${
+        return `${domain}/?link=${
             encodeURIComponent(window.location.href)}&apn=${
             APN}&ibi=${
             IBI}&isi=${