Add equivalent androidx proguard rules (#10138)

Author: PureWeen

.nuspec/proguard.cfg

@@ -1,9 +1,14 @@
 -keep class android.support.v7.widget.FitWindowsFrameLayout { *; }
 -dontwarn android.support.v7.widget.FitWindowsFrameLayout
+-keep class androidx.appcompat.widget.FitWindowsFrameLayout { *; }
+-dontwarn androidx.appcompat.widget.FitWindowsFrameLayout
 -keep class android.support.design.** { *; }
 -keep class android.support.multidex.MultiDexApplication { *; }
+-keep class androidx.multidex.MultiDexApplication { *; }
 -keep class android.support.design.internal.BaselineLayout { *; }
 -dontwarn android.support.design.internal.BaselineLayout
+-keep class com.google.android.material.internal.BaselineLayout { *; }
+-dontwarn com.google.android.material.internal.BaselineLayout
 -keep class com.google.firebase.provider.FirebaseInitProvider { *; }
 -keep class androidx.appcompat.widget.AlertDialogLayout { *; }
 -keep class androidx.appcompat.widget.DialogTitle { *; }