[SL.Core] move internals into a nested namespace

src/SixLabors.Core/Memory/ArrayPoolMemoryAllocator.Buffer{T}.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Buffers;
 using System.Runtime.InteropServices;
+using SixLabors.Memory.Internals;
 
 namespace SixLabors.Memory
 {

src/SixLabors.Core/Memory/BasicArrayBuffer.cs → src/SixLabors.Core/Memory/Internals/BasicArrayBuffer.cs

@@ -4,7 +4,7 @@
 using System;
 using System.Runtime.CompilerServices;
 
-namespace SixLabors.Memory
+namespace SixLabors.Memory.Internals
 {
     /// <summary>
     /// Wraps an array as an <see cref="IManagedByteBuffer"/> instance.

src/SixLabors.Core/Memory/BasicByteBuffer.cs → src/SixLabors.Core/Memory/Internals/BasicByteBuffer.cs

@@ -1,7 +1,7 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-namespace SixLabors.Memory
+namespace SixLabors.Memory.Internals
 {
     /// <summary>
     /// Provides an <see cref="IManagedByteBuffer"/> based on <see cref="BasicArrayBuffer{T}"/>.

src/SixLabors.Core/Memory/ManagedBufferBase.cs → src/SixLabors.Core/Memory/Internals/ManagedBufferBase.cs

@@ -4,7 +4,7 @@
 using System.Buffers;
 using System.Runtime.InteropServices;
 
-namespace SixLabors.Memory
+namespace SixLabors.Memory.Internals
 {
     /// <summary>
     /// Provides a base class for <see cref="IMemoryOwner{T}"/> implementations by implementing pinning logic for <see cref="MemoryManager{T}"/> adaption.

src/SixLabors.Core/Memory/SimpleGcMemoryAllocator.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System.Buffers;
+using SixLabors.Memory.Internals;
 
 namespace SixLabors.Memory
 {