snapshots should allow stepping through topologies

[acud]

currently a snapshot gives us just one topology that we would like to establish and work with.

this, however, infers that when we would like to change the topology to get a specific result (i.e. add more nodes in a pivot topology in order to move the kademlia depth of the pivot node) we must brute force this during the simulation.

this is a very costly operation and is not CI friendly.

we should be able to step our simulations between different states, allowing us to bootstrap more nodes whose addresses we know preemptively and add/remove them from the topology in order to achieve a certain deterministic result.

simulations should thus be able to have a recipe that can step between different topologies with ease, this recipe should be simple and should just allow to add/remove nodes.