Refactor Chunk method visibility and clean up preprocessor directives

Author: gehongyan

src/Kook.Net.Core/Extensions/CollectionExtensions.cs

@@ -37,6 +37,7 @@ public IReadOnlyCollection<TValue> ToReadOnlyCollection<TSource>(IReadOnlyCollec
         public IReadOnlyCollection<TValue> ToReadOnlyCollection(Func<int> countFunc) =>
             new CollectionWrapper<TValue>(query, countFunc);
 
+#if NETSTANDARD || NETFRAMEWORK
         public IEnumerable<TValue[]> Chunk(int size)
         {
             if (query is null)
@@ -103,10 +104,8 @@ static IEnumerable<TValue[]> ChunkIterator(IEnumerable<TValue> source, int size)
                 }
             }
         }
-    }
-
-#if NETSTANDARD || NETFRAMEWORK
 #endif
+    }
 }
 
 [DebuggerDisplay("{DebuggerDisplay,nq}")]