core/state: convert prefetcher to concurrent per-trie loader

accounts/abi/bind/backends/simulated.go

core/blockchain.go

core/state/state_object.go

core/state/state_test.go

core/state/statedb.go

core/state/statedb_test.go

core/state/trie_prefetcher.go

eth/api_tracer.go

miner/worker.go