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/RemoteBugreportActivity.java

@@ -17,7 +17,6 @@ package com.android.settings;
 
 import android.annotation.Nullable;
 import android.app.Activity;
-import android.app.AlertDialog;
 import android.app.admin.DevicePolicyManager;
 import android.content.DialogInterface;
 import android.content.Intent;
@@ -25,6 +24,8 @@ import android.os.Bundle;
 import android.os.UserHandle;
 import android.util.Log;
 
+import androidx.appcompat.app.AlertDialog;
+
 /**
  * UI for the remote bugreport dialog. Shows one of 3 possible dialogs:
  * <ul>