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.Test/HashMapBenchmark.cs

@@ -0,0 +1,114 @@
+using BenchmarkDotNet.Attributes;
+using Misaki.HighPerformance.LowLevel.Collections;
+
+namespace Misaki.HighPerformance.Test;
+
+public class HashMapBenchmark
+{
+    private UnsafeHashMap<int, float> _unsafeHashMap;
+    private Dictionary<int, float> _dictionary = null!;
+
+    [Params(10, 100, 1000)]
+    public int count;
+
+    [IterationSetup]
+    public void Setup()
+    {
+        //_unsafeHashMap = new UnsafeHashMap<int, float>(count, Allocator.Persistent);
+        _dictionary = new Dictionary<int, float>(count);
+
+        for (var i = 0; i < count; i++)
+        {
+            //_unsafeHashMap.Add(i, i);
+            _dictionary.Add(i, i);
+        }
+    }
+
+    [Benchmark]
+    public void UnsafeHashMapAdd()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            _unsafeHashMap.Add(count + i, i);
+        }
+    }
+
+    [Benchmark(Baseline = true)]
+    public void DictionaryAdd()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            _dictionary.Add(count + i, i);
+        }
+    }
+
+    public void UnsafeHashMapRemove()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            _unsafeHashMap.Remove(i);
+        }
+    }
+
+    public void DictionaryRemove()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            _dictionary.Remove(i);
+        }
+    }
+
+    public void UnsafeHashMapRandomRead()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            var value = Random.Shared.Next(0, count);
+            if (_unsafeHashMap.TryGetValue(value, out var result))
+            {
+                var r2 = result + result;
+            }
+        }
+    }
+
+    public void DictionaryRandomRead()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            var value = Random.Shared.Next(0, count);
+            if (_dictionary.TryGetValue(value, out var result))
+            {
+                var r2 = result + result;
+            }
+        }
+    }
+
+    public void UnsafeHashMapRandomWrite()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            var value = Random.Shared.Next(0, count);
+            if (_unsafeHashMap.TryGetValue(value, out var result))
+            {
+                _unsafeHashMap[value] = result + 1;
+            }
+        }
+    }
+
+    public void DictionaryRandomWrite()
+    {
+        for (var i = 0; i < count; i++)
+        {
+            var value = Random.Shared.Next(0, count);
+            if (_dictionary.TryGetValue(value, out var result))
+            {
+                _dictionary[value] = result + 1;
+            }
+        }
+    }
+
+    [IterationCleanup]
+    public void Cleanup()
+    {
+        //_unsafeHashMap.Dispose();
+    }
+}