Use string instead of String (dotnet#4602)

* Use string instead of String * Update Form1.cs * Re-trigger build

Author: Youssef1313

samples/snippets/csharp/VS_Snippets_Winforms/System.ComponentModel.IPropertyChangeExample/CS/Form1.cs

@@ -81,15 +81,15 @@ public class DemoCustomer : INotifyPropertyChanged
  {
  // These fields hold the values for the public properties.
  private Guid idValue = Guid.NewGuid();
- private string customerNameValue = String.Empty;
- private string phoneNumberValue = String.Empty;
+ private string customerNameValue = string.Empty;
+ private string phoneNumberValue = string.Empty;
 
  public event PropertyChangedEventHandler PropertyChanged;
 
  // This method is called by the Set accessor of each property.
  // The CallerMemberName attribute that is applied to the optional propertyName
  // parameter causes the property name of the caller to be substituted as an argument.
- private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
+ private void NotifyPropertyChanged([CallerMemberName] string propertyName = "")
  {
  if (PropertyChanged != null)
  {
@@ -156,4 +156,4 @@ public string PhoneNumber
  }
  // </snippet9>
 }
-// </snippet1>
+// </snippet1>