Import the window extension libary in the Settings app

Test: Rebuilt apk and run apk successfully.
Bug: 196939216
Change-Id: If9040ae9a1c72097e4964c8d40ea9785cf2f01dc

proguard.flags

@@ -66,3 +66,8 @@
 -keepclasseswithmembers class * extends com.android.settings.slices.SliceBackgroundWorker {
     public <init>(android.content.Context, android.net.Uri);
 }
+
+# Keep WM Jetpack classes and callbacks
+-keep class androidx.window.extensions.** { *; }
+-dontwarn androidx.window.extensions.**
+-keep class androidx.window.** { *; }