Implement a component that stores the values of the used space of
containers. The storage allows you to write several values for a fixed
container and epoch number, and read the averaged estimates of all
accumulated values. All values are stored in memory. This component is
planned to be used as an accumulator of opinions from various network
participants about the fullness of the container.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
