Make requested changes

Prevent breaking change by creating a new ctor

Update obsolete message

src/Umbraco.Core/IO/ViewHelper.cs

@@ -12,7 +12,7 @@ public class ViewHelper : IViewHelper
         private readonly IFileSystem _viewFileSystem;
         private readonly IDefaultViewContentProvider _defaultViewContentProvider;
 
-        [Obsolete("Inject IViewHelper instead")]
+        [Obsolete("Use ctor with all params")]
         public ViewHelper(IFileSystem viewFileSystem) => _viewFileSystem = viewFileSystem ?? throw new ArgumentNullException(nameof(viewFileSystem));
 
         public ViewHelper(FileSystems fileSystems, IDefaultViewContentProvider defaultViewContentProvider)

src/Umbraco.Web.BackOffice/Controllers/TemplateController.cs

@@ -3,6 +3,7 @@
 using System.Linq;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.Mvc;
+using Microsoft.Extensions.DependencyInjection;
 using Umbraco.Cms.Core;
 using Umbraco.Cms.Core.IO;
 using Umbraco.Cms.Core.Mapping;
@@ -12,6 +13,7 @@
 using Umbraco.Cms.Core.Strings;
 using Umbraco.Cms.Web.Common.Attributes;
 using Umbraco.Cms.Web.Common.Authorization;
+using Umbraco.Cms.Web.Common.DependencyInjection;
 using Constants = Umbraco.Cms.Core.Constants;
 
 namespace Umbraco.Cms.Web.BackOffice.Controllers
@@ -38,6 +40,15 @@ public TemplateController(
             _defaultViewContentProvider = defaultViewContentProvider ?? throw new ArgumentNullException(nameof(defaultViewContentProvider));
         }
 
+        [Obsolete("Use ctor will all params")]
+        public TemplateController(
+            IFileService fileService,
+            IUmbracoMapper umbracoMapper,
+            IShortStringHelper shortStringHelper)
+            : this(fileService, umbracoMapper, shortStringHelper, StaticServiceProvider.Instance.GetRequiredService<IDefaultViewContentProvider>())
+        {
+        }
+
         /// <summary>
         /// Gets data type by alias
         /// </summary>