Revert "Add code sharing sample (#1444)" (#1464)

This reverts commit fc6222ebc8.

code_sharing/client/pubspec.yaml

@@ -1,23 +0,0 @@
-name: client
-description: A Flutter app which communicates with a Dart backend using shared business logic.
-publish_to: "none"
-version: 1.0.0+1
-
-environment:
-  sdk: ">=2.18.1 <3.0.0"
-
-dependencies:
-  cupertino_icons: ^1.0.2
-  flutter:
-    sdk: flutter
-  http: ^0.13.5
-  shared:
-    path: ../server/shared
-
-dev_dependencies:
-  flutter_lints: ^2.0.0
-  flutter_test:
-    sdk: flutter
-
-flutter:
-  uses-material-design: true