Add credential management app preference to Settings

Background
* This is part of the work to support
  a credential management app on
  unmanaged devices.
Changes
* Add a preference controller which will only
  be enabled if there is a credential management app.
* Add a fragment to display details on the credential
  management app and its policy. Add a remove button
  to remove the credential management app.
* Link CredentialManagementAppAdapter to new fragment
  and add expander.

Manual Testing
* Verify preference is disabled if there is no credential
  management app.
* Verify preference summary shows credential mangement
  app name if a credential management app exists.
* Verify fragment details page displays the
  authentication policy correctly.

Bug: 165641221
Test: Manual testing
      make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.security.CredentialManagementAppFragmentTest
      make RunSettingsRoboTests -j ROBOTEST_FILTER=com.android.settings.security.CredentialManagementAppControllerTest
Change-Id: I06d6b88d0c89022f7a6cbf3031834defcb54bd51

res/drawable/ic_undo_24.xml

@@ -0,0 +1,25 @@
+<!--
+Copyright (C) 2020 The Android Open Source Project
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+         http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+-->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="24dp"
+        android:height="24dp"
+        android:viewportWidth="24"
+        android:viewportHeight="24"
+        android:tint="?attr/colorControlNormal">
+    <path
+        android:fillColor="@android:color/white"
+        android:pathData="M14.1,8H7.83l2.59,-2.59L9,4 4,9l5,5 1.41,-1.41L7.83,10h6.27c2.15,0 3.9,1.57 3.9,3.5S16.25,17 14.1,17H7v2h7.1c3.25,0 5.9,-2.47 5.9,-5.5S17.35,8 14.1,8z"/>
+</vector>