Help users understand hot reload when using a statement management package

This is the tooling side of the issue of https://github.com/flutter/website/issues/3566. Various statement management packages apparently have different implications to what code becomes reloadable, and some of the behaviors are not expected by app developers. It would be great if the IDE can help the user in two ways:

- Let users know when they wrote code that is not going to run after hot reload
- Let users know how they can tweak their code to make it hot reloadable.

Maybe we can try out a few statement management packages in the next team hackathon?

Start by reading the Flutter website issue 3566 and comparing the hot-reload behavior of several statement management packages, as suggested in this issue. The repository and relevant files, tests, entry points, and a concrete completion criterion are not identified, so the scope needs clarification before implementation.

Written by the indexing model from the issue text.