Access count was not incremented when chunk was retrieved
from cache. So the garbage collector might have deleted the most
frequently accessed chunk from disk.
Co-authored-by: NFerenc Szabo <ferenc.szabo@ethereum.org>

Co-authored-by: NJanos Guljas <janos@resenje.org>
Co-authored-by: NBalint Gabor <balint.g@gmail.com>
Co-authored-by: NAnton Evangelatov <anton.evangelatov@gmail.com>
Co-authored-by: NViktor Trón <viktor.tron@gmail.com>

* swarm/network, swarm/storage: validate default chunk size

* swarm/bmt, swarm/network, swarm/storage: update BMT hash initialisation

* swarm/bmt: move segmentCount to tests

* swarm/chunk: change chunk.DefaultSize to be untyped const

* swarm/storage: add size validator

* swarm/storage: add chunk size validation to localstore

* swarm/storage: move validation from localstore to validator

* swarm/storage: global chunk rules in MRU