core: fix broken tests due to API changes + linter

core/blockchain_test.go

core/state/iterator_test.go

core/state/snapshot/difflayer.go

core/state/snapshot/difflayer_test.go

core/state/snapshot/disklayer_test.go

core/state/snapshot/generate.go

core/state/snapshot/iteration.md

core/state/snapshot/iterator_binary.go

core/state/snapshot/iterator_fast.go

core/state/snapshot/iterator_test.go

core/state/snapshot/journal.go

core/state/snapshot/sort.go

core/state/state_test.go

core/state/statedb_test.go

core/state/sync_test.go

core/tx_pool_test.go

core/vm/gas_table_test.go

les/odr_test.go