Add to Chunk<T> method AsBestHardwareSpan(), StepBestHardwareSpan

[Iwan91]

Not all hardware support Span512.
We can check this by Vector512.IsHardwareAccelerated.

In class Chunk we could get something like that:

    public              Span<TTo>  AsBestHardwareSpan<TTo>() where TTo : struct
    {
        if (Vector512.IsHardwareAccelerated)
        {
            return AsSpan512<TTo>();
        }
        
        return Vector256.IsHardwareAccelerated ? AsSpan256<TTo>() : AsSpan128<TTo>();
    }
    
    public int StepBestHardwareSpan
    {
        get{
            
            if (Vector512.IsHardwareAccelerated)
            {
                return StepSpan512;
            }
            
            return Vector256.IsHardwareAccelerated ? StepSpan256 : StepSpan128;
        }
    }

Then in code that use vectorization/SIMD we could use best case that support our hardware.
Maybe we could somehow check this only once to avoid every time "if" because I think that support won't change in runtime.

What do you think about it?

[friflo]

Hm,
I don't like the condition in this simple method.
AsBestHardwareSpan<>() is a utility method.

In this library I try to avoid utility methods at all.
This keeps the API surface as small as possible and avoids confusion.
This principle is applicable also to this method.