Check for modern web libraries to determine if an app is a web app

We currently check for the presence of `dart:html` in the connected app to determine whether it is a web application.

https://github.com/flutter/devtools/blob/master/packages/devtools_app_shared/lib/src/service/connected_app.dart#L88-L89

We should make this an OR check with a `package:web` or `dart:js_interop` library. Leaving the dart:html condition we allow us to still support apps using dart:html (e.g. g3).

Start in packages/devtools_app_shared/lib/src/service/connected_app.dart at lines 88-89, where the connected app is identified as a web application. Trace the existing dart:html check and update the condition to also recognize package:web or dart:js_interop while preserving dart:html support. Done means apps using any of these libraries are detected as web apps.

Written by the indexing model from the issue text.