feat(unsafe-collections)!: move span/array copy methods to core

CopyTo, CopyFrom, ToArray, and ToList are now implemented as instance methods on UnsafeArray<T> and UnsafeList<T>, replacing the previous extension methods. This change enables more direct and efficient copying between unsafe collections and managed spans, arrays, and lists, with overloads for ranges and resizing as needed. Extension methods for these operations have been removed. Minor cleanup and usage updates are included.

BREAKING CHANGE: Extension methods for copying and converting between unsafe collections and spans/arrays/lists have been removed. Use the new instance methods instead.

Misaki.HighPerformance.LowLevel/Buffer/AllocationManager.cs

@@ -1,7 +1,3 @@
-#if DEBUG
-#define ENABLE_DEBUG_LAYER
-#endif
-
 using Misaki.HighPerformance.Collections;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;