Flutter Minimalist state management example

Because the official Flutter website mentions 13 different ways to do state management, why not
yet another state management example. The official Flutter cupertino-store codelabs is used as
basis, but instead of using the Provider pattern the Minimalist approach is
used. Shout out to @mvolpato for sharing it and @suragch1 for writing it.

Cupertino-store minimalist approach