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/y-leveldb/README.md

@@ -0,0 +1,114 @@
+# LevelDB database adapter for [Yjs](https://github.com/yjs/yjs)
+
+LevelDB is a fast embedded database. It is the underlying technology of IndexedDB.
+
+Internally, y-leveldb uses [`level`](https://github.com/Level/level) which
+allows to exchange the storage medium for a different supported database.
+Hence this adapter also supports rocksdb, lmdb, and many more..
+
+* Persistent storage for the server
+* Exchangeable storage medium
+* Can be used in [y-websocket](https://github.com/yjs/y-websocket)
+* A single y-leveldb instance can handle many documents.
+
+## Use it
+
+```sh
+npm install y-leveldb --save
+```
+
+```js
+import { LeveldbPersistence } from 'y-leveldb'
+
+const persistence = new LeveldbPersistence('./storage-location')
+
+const ydoc = new Y.Doc()
+ydoc.getArray('arr').insert(0, [1, 2, 3])
+ydoc.getArray('arr').toArray() // => [1, 2, 3]
+
+// store document updates retrieved from other clients
+persistence.storeUpdate('my-doc', Y.encodeStateAsUpdate(ydoc))
+
+// when you want to sync, or store data to a database,
+// retrieve the temporary Y.Doc to consume data
+persistence.getYDoc('my-doc').getArray('arr') // [1, 2, 3]
+```
+
+## API
+
+### `persistence = LeveldbPersistence(storageLocation, [{ [level] }])`
+
+Create a y-leveldb persistence instance.
+
+You can use any levelup-compatible adapter.
+
+```js
+import { LeveldbPersistence } from 'y-leveldb'
+import level from 'level-mem'
+
+const persistence = new LeveldbPersistence('./storage-location', { level })
+```
+
+#### `persistence.getYDoc(docName: string): Promise<Y.Doc>`
+
+Create a Y.Doc instance with the data persistet in leveldb. Use this to
+temporarily create a Yjs document to sync changes or extract data.
+
+#### `persistence.storeUpdate(docName: string, update: Uint8Array): Promise`
+
+Store a single document update to the database.
+
+#### `persistence.getStateVector(docName: string): Promise<Uint8Array>`
+
+The state vector (describing the state of the persisted document - see
+[Yjs docs](https://github.com/yjs/yjs#Document-Updates)) is maintained in a separate
+field and constantly updated.
+
+This allows you to sync changes without actually creating a Yjs document.
+
+#### `persistence.getDiff(docName: string, stateVector: Uint8Array): Promise<Uint8Array>`
+
+Get the differences directly from the database. The same as
+`Y.encodeStateAsUpdate(ydoc, stateVector)`.
+
+#### `persistence.clearDocument(docName: string): Promise`
+
+Delete a document, and all associated data from the database.
+
+#### `persistence.setMeta(docName: string, metaKey: string, value: any): Promise`
+
+Persist some meta information in the database and associate it with a document.
+It is up to you what you store here. You could, for example, store credentials
+here.
+
+#### `persistence.getMeta(docName: string, metaKey: string): Promise<any|undefined>`
+
+Retrieve a store meta value from the database. Returns undefined if the
+`metaKey` doesn't exist.
+
+#### `persistence.delMeta(docName: string, metaKey: string): Promise`
+
+Delete a store meta value.
+
+#### `persistence.getAllDocNames(docName: string): Promise<Array<string>>`
+
+Retrieve the names of all stored documents.
+
+#### `persistence.getAllDocStateVectors(docName: string): Promise<Array<{ name:string,clock:number,sv:Uint8Array}`
+
+Retrieve the state vectors of all stored documents. You can use this to sync
+two y-leveldb instances.
+
+Note: The state vectors might be outdated if the associated document is not
+yet flushed. So use with caution.
+
+#### `persistence.flushDocument(docName: string): Promise` (dev only)
+
+Internally y-leveldb stores incremental updates. You can merge all document
+updates to a single entry. You probably never have to use this.
+
+## License
+
+y-leveldb is licensed under the [MIT License](./LICENSE).
+
+<kevin.jahns@protonmail.com>