Add a backing field for EditorUIAlias and track changes when its set. (#19733)

* Add a backing field for EditorUIAlias and track changes when its set.

* Add previously failing unit test to verify fix.

* Aligned backing field casing with property name.

---------

Co-authored-by: Andy Butland <abutland73@gmail.com>

tests/Umbraco.Tests.UnitTests/Umbraco.Core/Models/DataTypeTests.cs

@@ -0,0 +1,35 @@
+// Copyright (c) Umbraco.
+// See LICENSE for more details.
+
+using NUnit.Framework;
+using Umbraco.Cms.Core.Models;
+using Umbraco.Cms.Tests.Common.Builders;
+using Umbraco.Cms.Tests.Common.Builders.Extensions;
+
+namespace Umbraco.Cms.Tests.UnitTests.Umbraco.Core.Models;
+
+[TestFixture]
+public class DataTypeTests
+{
+    [Test]
+    public void Can_Update_And_Verify_Dirty_Properties()
+    {
+        var dataType = new DataTypeBuilder()
+            .WithName("Test Data Type")
+            .WithDatabaseType(ValueStorageType.Ntext)
+            .Build();
+
+        dataType.ResetDirtyProperties();
+
+        dataType.DatabaseType = ValueStorageType.Nvarchar;
+        dataType.EditorUiAlias = "Test.EditorUiAlias";
+
+        var dirtyProperties = dataType.GetDirtyProperties().OrderBy(x => x).ToList();
+
+        Assert.IsTrue(dataType.IsPropertyDirty(nameof(dataType.DatabaseType)));
+        Assert.IsTrue(dataType.IsPropertyDirty(nameof(dataType.EditorUiAlias)));
+
+        Assert.AreEqual(2, dirtyProperties.Count);
+        Assert.AreEqual($"{nameof(dataType.DatabaseType)},{nameof(dataType.EditorUiAlias)}", string.Join(",", dirtyProperties));
+    }
+}