Add image processing and memory management features

Added new namespace `Misaki.HighPerformance.Image` for image processing, including classes for animated GIF handling and memory management.
Added `AnimatedFrameResult` class for individual frames in animated images.
Added `AnimatedGifEnumerator` class for enumerating frames in animated GIFs.
Added `ColorComponents` enum for different color formats.
Added `ImageInfo` struct for image dimensions and color components.
Added `CRuntime` class for low-level memory management functions.
Added `MemoryStats` class to track memory allocation statistics.
Added utility functions for creating multi-dimensional arrays.
Added new structures for fixed-size UTF-8 encoded strings.
Added benchmarking classes to test new memory management features.

Changed `StbImage.cs` to include new namespaces and functionality for image data manipulation.
Changed project files to target .NET 9.0 and enable new features.
Changed `Arena.cs` and `DynamicArena.cs` to use `nuint` for size parameters.
Changed `BitSet.cs` to enhance bit manipulation methods.
Changed `Program.cs` to run `FunctionPtrBenchmark` for performance testing.

Removed memory tracking code from `AllocationManager.cs`, including the `_allocated` dictionary and related logic.
Removed `Free` method from `IAllocator.cs` interface.
Removed `UNSAFE_COLLECTION_CHECK` preprocessor directive from the codebase.

Refactored various files to improve organization, moving from `Unsafe` to `LowLevel` namespace.
Refactored `MemoryUtilities` class to include new memory operation methods.
Refactored `UnsafeUtilities.cs` to support new collection structures.

Misaki.HighPerformance.Image/ImageInfo.cs

@@ -0,0 +1,40 @@
+using System.IO;
+
+namespace Misaki.HighPerformance.Image
+{
+#if !STBSHARP_INTERNAL
+    public
+#else
+	internal
+#endif
+    struct ImageInfo
+    {
+        public int Width;
+        public int Height;
+        public ColorComponents ColorComponents;
+        public int BitsPerChannel;
+
+        public static unsafe ImageInfo? FromStream(Stream stream)
+        {
+            int width, height, comp;
+            var context = new StbImage.stbi__context(stream);
+
+            var is16Bit = StbImage.stbi__is_16_main(context) == 1;
+            StbImage.stbi__rewind(context);
+
+            var infoResult = StbImage.stbi__info_main(context, &width, &height, &comp);
+            StbImage.stbi__rewind(context);
+
+            if (infoResult == 0)
+                return null;
+
+            return new ImageInfo
+            {
+                Width = width,
+                Height = height,
+                ColorComponents = (ColorComponents)comp,
+                BitsPerChannel = is16Bit ? 16 : 8
+            };
+        }
+    }
+}