Set overlayable for CarsystemUI NavBar

Bug: 142822006
Test: Nav icons should be hidden accordingly
Change-Id: I88d954c03076dfa9489564e0a9684be265f4c886

packages/CarSystemUI/res/xml/overlayable.xml

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- 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.
+-->
+
+<resources>
+    <overlayable name="SystemBarsLayouts">
+        <policy type="product|signature">
+            <item type="layout" name="car_navigation_bar" />
+        </policy>
+    </overlayable>
+</resources>