Move map cleaner functionality into netmap contract

[roman-khimov]

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

I'm always frustrated when I realize that ten lines in netmap contract can save us hundreds lines in IR. We've got a code in IR that tracks node heartbeats and forcibly removes inactive nodes (via additional transactions).

Describe the solution you'd like

This can be done automatically by the netmap contract since it knows precisely when addpeer/updatepeer happen and filter things out on epoch tick.

Additional context

#298
nspcc-dev/neofs-node#1914