Move SampleTurboModule out of core and into it's own package

[jonthysell]

Summary

SampleTurboModule is defined in RN core, but really it's really only there to be used by the RNTester example page.

In PR #13533, we added RNW's SampleTurboModule impl in RNW core, but we have the opportunity to move it into its own package.

Motivation

So that end customers can actually use SampleTurboModule as a sample they can duplicate.

Basic Example

1. New private package in packages/react-native-sample-turbo-module
2. Update each of our apps that uses RNTester js (e2e-test-app, e2e-trest-app-fabric, playground, etc.) to depend on that package

Open Questions

Will it be possible for us to do this without requiring the upstream module to be moved out of core? Is this sample perhaps a good way of testing how to add platform support to a module even if you can't modify the package that contains its spec/definition?