[MM-55152] Add new Desktop API endpoints, improve preload script, some clean-up (#2900)

* Add constants for app info, add to API

* Migrate history button

* Converted calls API over to context bridge, removed some unnecessary logging

* Convert to TS, add types for web app to consume

* Fix tests, prune

* Fix lint

* More changes to support the legacy API

* Force legacy code off, add support for unreads/mentions/expired through the API

* Fix issues with cross-tab login, removed need for log in/log out signalling

* Fixed test, typos

* Change package name for types

* Add some other stuff to the types

* PR feedback

* More feedback

* Use npm package

* Change types and API to provide off listeners

* Version number

* Lock

* Fix typo

* Add sessionID for calls

api-types/lib/index.js

@@ -0,0 +1,4 @@
+"use strict";
+// Copyright (c) 2016-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+Object.defineProperty(exports, "__esModule", { value: true });