Default android app icon should use <adaptive-icon>

Test: install apk without application icon. manually check on default launcher.

b/34948318

Change-Id: I8a7e5f4343d9ed3eb32cbfa69857aa6264107654

core/res/res/drawable/sym_def_app_icon.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@android:color/white" />
+    <foreground android:drawable="@mipmap/sym_def_app_icon_maskable" />
+</adaptive-icon>