Migrate all AlertDialogs to AndroidX version

This CL only changed AlertDialog imports.
So, reviewer can review it easily.

Change-Id: I097bc44394195b14287f4f920c570ac8653f356a
Fixes: 111413092
Test: This CL can't pass Robo test.

src/com/android/settings/RegulatoryInfoDisplayActivity.java

@@ -17,7 +17,6 @@
 package com.android.settings;
 
 import android.app.Activity;
-import android.app.AlertDialog;
 import android.content.DialogInterface;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
@@ -34,6 +33,7 @@ import android.widget.TextView;
 import java.util.Locale;
 
 import androidx.annotation.VisibleForTesting;
+import androidx.appcompat.app.AlertDialog;
 
 /**
  * {@link Activity} that displays regulatory information for the "Regulatory information"