FRE-600: Fix code review blockers

- Consolidated duplicate UndoManagers to single instance
- Fixed connection promise to only resolve on 'connected' status
- Fixed WebSocketProvider import (WebsocketProvider)
- Added proper doc.destroy() cleanup
- Renamed isPresenceInitialized property to avoid conflict

Co-Authored-By: Paperclip <noreply@paperclip.ing>

node_modules/level-packager/UPGRADING.md

@@ -0,0 +1,15 @@
+# Upgrade Guide
+
+This document describes breaking changes and how to upgrade. For a complete list of changes including minor and patch releases, please refer to the [changelog](CHANGELOG.md).
+
+## v5
+
+Upgraded to [`levelup@4`](https://github.com/Level/levelup/blob/v4.0.0/UPGRADING.md#v4) and [`encoding-down@6`](https://github.com/Level/encoding-down/blob/v6.0.0/UPGRADING.md#v6). We recommend to pair `level-packager@5` only with a store based on `abstract-leveldown` >= 6. Please follow the earlier links for more information.
+
+## v4
+
+The `test.js` file was rewritten to test the `level-packager` api and is no longer part of the api. Implementations based on `level-packager` should instead use the tests in the `abstract/` folder.
+
+## v3
+
+Dropped support for node 4. No other breaking changes.