Migrate Messaging to androidx.

Test: make messaging
Bug: 76692459
Change-Id: I9103450622f129311545648ac75f5b2f9fc2d04a

res/layout/contact_picker_fragment.xml

@@ -21,7 +21,7 @@
     android:layout_height="match_parent"
     android:orientation="vertical">
 
-    <android.support.v7.widget.Toolbar
+    <androidx.appcompat.widget.Toolbar
         android:id="@+id/toolbar"
         android:layout_height="wrap_content"
         android:layout_width="match_parent"
@@ -58,7 +58,7 @@
 
         </com.android.messaging.ui.MaxHeightScrollView>
 
-    </android.support.v7.widget.Toolbar>
+    </androidx.appcompat.widget.Toolbar>
 
     <FrameLayout
         android:layout_width="match_parent"