[dds/tree] UndoRedoHandler is not exported from experimental/dds/tree/src/index.ts

[TheLarkInn]

Describe the bug

UndoRedoHandler is not exported from experimental/dds/tree/src/index.ts. This is problematic because when you are using typescripts "moduleResolution": "Bundler", it becomes impossible to override or work around this bug by using deep imports.

Discovered this in version 2.4, but looking at 2.10/GitHub Source it appears this is still a problem
 

To Reproduce

Steps to reproduce the behavior:

1. Consume this API in a typescript file with moduleResolution: 'bundler':

import type { SharedTreeUndoRedoHandler } from '@fluid-experimental/tree';

2. See the typescript error that this package cannot be found.

Expected behavior

UndoRedoHandler should either have a proper package export entry in the package.json OR UndoRedoHandler should be exported from index.ts

[tylerbutler]

@microsoft/fluid-cr-tree - Is this on your radar?