Revert "Move `analyzer_cli` into the SDK."

pkg/analyzer_cli/test/data/package_with_sdk_extension/lib/foo.dart

Index: pkg/analyzer_cli/test/data/package_with_sdk_extension/lib/foo.dart
diff --git a/pkg/analyzer_cli/test/data/package_with_sdk_extension/lib/foo.dart b/pkg/analyzer_cli/test/data/package_with_sdk_extension/lib/foo.dart
deleted file mode 100644
index c56eef9599e8d9b906a5c27a7783da437ac89f62..0000000000000000000000000000000000000000
--- a/pkg/analyzer_cli/test/data/package_with_sdk_extension/lib/foo.dart
+++ /dev/null
@@ -1,5 +0,0 @@
-// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-void bar() {}