Make Address value object truly immutable

It's better to remove private property setters to make Address value object truly immutable. Otherwise, it's possible to change the object by setting properties inside its methods for example.

``` 
protected override IEnumerable<object> GetAtomicValues()
    {
       Street = "Blah blah blah";
       City = "Blah blah blah";

        // Using a yield return statement to return each element one at a time
        yield return Street;
        yield return City;
        yield return State;
        yield return Country;
        yield return ZipCode;
    }
```

src/Services/Ordering/Ordering.Domain/AggregatesModel/OrderAggregate/Address.cs

@@ -7,15 +7,15 @@ namespace Microsoft.eShopOnContainers.Services.Ordering.Domain.AggregatesModel.O
     public class Address
         :ValueObject
     {
-        public String Street { get; private set; }
+        public String Street { get; }
 
-        public String City { get; private set; }
+        public String City { get; }
 
-        public String State { get; private set; }
+        public String State { get; }
 
-        public String Country { get; private set; }
+        public String Country { get; }
 
-        public String ZipCode { get; private set; }
+        public String ZipCode { get; }
 
         private Address() { }