Enhance memory management and data structures

Updated `CollectionBenchmark` for setup/cleanup methods,
streamlined benchmarking in `Program.cs`, and improved
documentation in `AllocationOption` and `Allocator` enums.
Made `Enumerator` structs public in several collections
and clarified constructor parameters. Introduced a new
`UnsafeStack` struct for stack operations. Enhanced
`AllocationManager` with better memory tracking and
management, ensuring proper allocation and disposal.

Misaki.HighPerformance.Unsafe/Collections/UnsafeHashSet.cs

@@ -13,7 +13,7 @@ namespace Misaki.HighPerformance.Unsafe.Collections;
 public unsafe struct UnsafeHashSet<T> : IUnsafeCollection<T>, IEnumerable<T>
     where T : unmanaged, IEquatable<T>
 {
-    private struct Enumerator : IEnumerator<T>
+    public struct Enumerator : IEnumerator<T>
     {
         internal HashMapHelper<T>.Enumerator _enumerator;