Added missing file headers

Author: Sergio0694

Microsoft.Toolkit.HighPerformance/Streams/MemoryStream.ThrowExceptions.cs

@@ -1,4 +1,8 @@
-using System;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
 using System.IO;
 
 namespace Microsoft.Toolkit.HighPerformance.Streams

Microsoft.Toolkit.HighPerformance/Streams/MemoryStream.Validate.cs

@@ -1,4 +1,8 @@
-using System.IO;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.IO;
 using System.Runtime.CompilerServices;
 
 namespace Microsoft.Toolkit.HighPerformance.Streams

Microsoft.Toolkit.HighPerformance/Streams/MemoryStream.cs

@@ -1,4 +1,8 @@
-using System;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
 using System.Buffers;
 using System.Diagnostics.Contracts;
 using System.IO;

Microsoft.Toolkit.HighPerformance/Streams/Sources/ArrayOwner.cs

@@ -1,4 +1,8 @@
-using System;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using Microsoft.Toolkit.HighPerformance.Extensions;

Microsoft.Toolkit.HighPerformance/Streams/Sources/Interfaces/ISpanOwner.cs

@@ -1,4 +1,8 @@
-using System;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
 
 namespace Microsoft.Toolkit.HighPerformance.Streams
 {

Microsoft.Toolkit.HighPerformance/Streams/Sources/MemoryManagerOwner.cs

@@ -1,4 +1,8 @@
-using System;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
 using System.Buffers;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;