initial work to split into dart_filament and flutter_filament

dart_filament/example_cli/test/example_cli_test.dart

@@ -0,0 +1,8 @@
+import 'package:example_cli/example_cli.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('calculate', () {
+    expect(calculate(), 42);
+  });
+}