Fix AndroidX Layouts

src/ControlGallery/src/Xamarin.Forms.ControlGallery.Android/Resources/layout/Tabbar.axml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<android.support.design.widget.TabLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<com.google.android.material.tabs.TabLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:id="@+id/sliding_tabs"
     android:layout_width="match_parent"

src/ControlGallery/src/Xamarin.Forms.ControlGallery.Android/Resources/layout/Toolbar.axml

@@ -1,4 +1,4 @@
-<android.support.v7.widget.Toolbar
+<androidx.appcompat.widget.Toolbar
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/toolbar"
     android:layout_width="match_parent"