Performance: Request cache referenced entities when saving documents with block editors (#20590)

* Added request cache to content and media lookups in mult URL picker.

* Allow property editors to cache referenced entities from block data.

* Update src/Umbraco.Infrastructure/PropertyEditors/MultiUrlPickerValueEditor.cs

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Add obsoletions.

* Minor spellcheck

* Ensure request cache is available before relying on it.

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: kjac <kja@umbraco.dk>

tests/Umbraco.Tests.UnitTests/Umbraco.Core/PropertyEditors/Validators/MultiUrlPickerValueEditorValidationTests.cs

@@ -2,6 +2,7 @@ using System.ComponentModel.DataAnnotations;
 using Microsoft.Extensions.Logging;
 using Moq;
 using NUnit.Framework;
+using Umbraco.Cms.Core.Cache;
 using Umbraco.Cms.Core.IO;
 using Umbraco.Cms.Core.Models.Validation;
 using Umbraco.Cms.Core.PropertyEditors;
@@ -68,7 +69,8 @@ internal class MultiUrlPickerValueEditorValidationTests
             new SystemTextJsonSerializer(new DefaultJsonSerializerEncoderFactory()),
             Mock.Of<IIOHelper>(),
             Mock.Of<IContentService>(),
-            Mock.Of<IMediaService>())
+            Mock.Of<IMediaService>(),
+            AppCaches.Disabled)
         {
             ConfigurationObject = new MultiUrlPickerConfiguration(),
         };