feat(find): implement maxn & minn for variadic count items

[dashjay]

After reviewing code in issue #224,I implemented a version in more convenient way, I do not agree to change the interface, because the interface of the base library once opened to change will cause a lot of dissatisfaction.

func MaxN[T constraints.Ordered](items ...T) T {
	return Max(items)
}

func MinN[T constraints.Ordered](items ...T) T {
	return Min(items)
}

[dashjay]

#224

[dashjay]

@samber Thank you for open such a nice package!
PTLA~