Move various Shell tests into a subdir.

mojo/shell/capability_filter_unittest.mojom

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-module mojo.shell;
-
-// The following two interfaces are implemented by a service application. Two
-// applications are started by a broker that connect to this service
-// application, one is limited by the broker to only see Safe while the other
-// can see both Safe and Unsafe.
-interface Safe { };
-interface Unsafe { };
-
-// Implemented by a service that records interfaces exposed to an application
-// and connection errors to a target application.
-interface Validator {
-  AddInterfaceCalled(string app_url,
-                     string service_url,
-                     string name,
-                     bool blocked);
-  ConnectionClosed(string from_url, string to_url);
-};