Refactor API

[fyrchik]

Current implementation heavily uses reflection and is used on a hot path in many places in neofs-node:

1. Shard sorting
2. Calculating container nodes for a placement policy.

It makes sense to optimize for common use-cases:

1. Uniform sorting.
2. Think about reusing memory and designing an appropriate API.
3. Use sync.Pool and see if it helps.

May be we could use generics here, but the task is not about this.

[fyrchik]

#3 provided perfomance improvements for the most common use-cases.
Let's not close this task, to see whether we can optimize this further.