[MM-19569] add notarization to osx app (#1086)

* [MM-19569] add notarization to release

also added signing verification on release
added electron-notarize to dev deps

* [MM-19569] fix semicolon

* [MM-19569] check that we are running on osx to notarize

scripts/notarize.js

@@ -0,0 +1,26 @@
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+// inspired by https://kilianvalkhof.com/2019/electron/notarizing-your-electron-application/
+require('dotenv').config();
+const {notarize} = require('electron-notarize');
+
+const config = require('../electron-builder.json');
+
+exports.default = async function notarizing(context) {
+  const {electronPlatformName, appOutDir} = context;
+  if (electronPlatformName !== 'darwin' || process.platform !== 'darwin') {
+    return;
+  }
+
+  const appName = context.packager.appInfo.productFilename;
+
+  await notarize({
+
+    // should we change it to appBundleId: 'com.mattermost.desktop',
+    appBundleId: config.appId,
+    appPath: `${appOutDir}/${appName}.app`,
+    appleId: process.env.APPLEID,
+    appleIdPassword: process.env.APPLEIDPASS,
+  });
+};