core/state/snapshot: implement storage iterator (#20971)

* core/state/snapshot: implement storage iterator

* core/state/snapshot, tests: implement helper function

* core/state/snapshot: fix storage issue

If an account is deleted in the tx_1 but recreated in the tx_2,
the it can happen that in this diff layer, both destructedSet
and storageData records this account. In this case, the storage
iterator should be able to iterate the slots belong to new account
but disable further iteration in deeper layers(belong to old account)

* core/state/snapshot: address peter and martin's comment

* core/state: address comments

* core/state/snapshot: fix test

core/state/snapshot/generate.go

@@ -42,7 +42,7 @@ var (
 )
 
 // generatorStats is a collection of statistics gathered by the snapshot generator
-// for  logging purposes.
+// for logging purposes.
 type generatorStats struct {
 	wiping   chan struct{}      // Notification channel if wiping is in progress
 	origin   uint64             // Origin prefix where generation started
@@ -167,7 +167,7 @@ func (dl *diskLayer) generate(stats *generatorStats) {
 		if err := rlp.DecodeBytes(accIt.Value, &acc); err != nil {
 			log.Crit("Invalid account encountered during snapshot creation", "err", err)
 		}
-		data := AccountRLP(acc.Nonce, acc.Balance, acc.Root, acc.CodeHash)
+		data := SlimAccountRLP(acc.Nonce, acc.Balance, acc.Root, acc.CodeHash)
 
 		// If the account is not yet in-progress, write it out
 		if accMarker == nil || !bytes.Equal(accountHash[:], accMarker) {