Create Pip package

Create a pip package allowing this to be called from another app, instead of being self-contained.

This library will need to have callbacks for commands, so that the app can respond to other commands than `update_color`

Review the current self-contained application and how it handles the `update_color` command. Define the pip package boundary and callback behavior for additional commands; done means the library can be installed and called from another app while supporting command callbacks.

Written by the indexing model from the issue text.