Properly wrap context-related NeoFS Client errors

[AnnaShaleva]

Is your feature request related to a problem? Please describe.

I'm using NeoFS Client to perform object get and object search requests with cancellation context. If context is cancelled by the caller's code, the rpc error: code = Canceled desc = context canceled error is returned from this method: https://github.com/nspcc-dev/neofs-sdk-go/blob/3d4a462485d427f15c26a1f8a31873dcc9500cd6/client/object_search.go#L140

This error is expected since context was explicitly cancelled. However, I can't identify this error with if errors.Is(err, context.Canceled) because it's not a wrapped error.

Describe the solution you'd like

context.Canceled and context.DeadlineExceeded should be recognizable by NeoFS client and should be returned as wrapped errors from all clients methods that work with context. We're at Go 1.22, multierror wrapping is supported.

Describe alternatives you've considered

Leave it as is, but it leads to the following code on the caller's side:

// isContextCanceledErr returns whether error is a wrapped [context.Canceled].
func isContextCanceledErr(err error) bool {
    return errors.Is(err, context.Canceled) ||
        strings.Contains(err.Error(), "context canceled")
}

[roman-khimov]

But if it happens server-side it can be a problem.