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

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?

Review the existing SampleTurboModule definition in RN core and the RNW implementation referenced by PR #13533. Trace its use in RNTester JS and the listed apps, including e2e-test-app, e2e-trest-app-fabric, and playground. Done means the private packages/react-native-sample-turbo-module package and required app dependencies are defined, with the upstream module question resolved.