Message validation ConsensusState eviction

[nkryuchkov]

Evict state entries older than 2 epochs

[moshe-blox]

@y0sher @nkryuchkov

what do you think to replace the ttlhash with a map that every slot we lock, unset the key from 64 slots ago, and then unlock?

[nkryuchkov]

@moshe-blox but what if there's a slot with no messages?

[y0sher]

@nkryuchkov @moshe-blox I think we should adjust this to fit alan/no-fork.

[nkryuchkov]

@y0sher Perhaps we need to consider trying to change ttlcache with an array or something like that