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/@jridgewell/trace-mapping/src/strip-filename.ts

@@ -0,0 +1,8 @@
+/**
+ * Removes everything after the last "/", but leaves the slash.
+ */
+export default function stripFilename(path: string | undefined | null): string {
+  if (!path) return '';
+  const index = path.lastIndexOf('/');
+  return path.slice(0, index + 1);
+}