[Panlingual] Implement entries of Panlingual in settings UI part.

- Path 1 : System -> Language & Input -> App Languages -> per app
 language
 - path 2 : System -> Apps -> App Info -> per app language
 Video: https://screencast.googleplex.com/cast/NjUyNTUzMDY0MTc5MzAyNHxjNTg2MzMwYS0yOA

Bug: 206854105
Test: local test pass
Test: atest pass

Change-Id: Ic06fa4f0c6ec68680eb828032b6e3f479b412dc4

res/layout/app_locale_details_description.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2021 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.
+-->
+
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="fill_parent"
+    android:layout_height="wrap_content"
+    android:gravity="center_horizontal" >
+    <TextView
+        android:id="@id/description"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginLeft="15dip"
+        android:layout_marginRight="6dip"
+        android:layout_marginTop="6dip"
+        android:textAlignment="center"/>
+
+</LinearLayout>