Migrated various IPublishedContent extension methods from web to core, removin use of service location.

Kept the original methods passing through to the core ones, providing the service located dependencies.
Used one of these migrated methods in the Umbraco.Infrastructure.PublishedCache project.

src/Umbraco.Infrastructure.PublishedCache/PublishedCacheBase.cs

@@ -10,6 +10,13 @@ namespace Umbraco.Web.PublishedCache
 {
     abstract class PublishedCacheBase : IPublishedCache
     {
+        private readonly IVariationContextAccessor _variationContextAccessor;
+
+        public PublishedCacheBase(IVariationContextAccessor variationContextAccessor)
+        {
+            _variationContextAccessor = variationContextAccessor ?? throw new ArgumentNullException(nameof(variationContextAccessor));
+
+        }
         public bool PreviewDefault { get; }
 
         protected PublishedCacheBase(bool previewDefault)
@@ -94,14 +101,11 @@ namespace Umbraco.Web.PublishedCache
 
         public virtual IEnumerable<IPublishedContent> GetByContentType(IPublishedContentType contentType)
         {
-            // TODO: move this extension method and get working again.
-
             // this is probably not super-efficient, but works
             // some cache implementation may want to override it, though
-            return Enumerable.Empty<IPublishedContent>();
-            //return GetAtRoot()
-            //    .SelectMany(x => x.DescendantsOrSelf())
-            //    .Where(x => x.ContentType.Id == contentType.Id);
+            return GetAtRoot()
+                .SelectMany(x => x.DescendantsOrSelf(_variationContextAccessor))
+                .Where(x => x.ContentType.Id == contentType.Id);
         }
     }
 }