all: simplify and fix database iteration with prefix/start (#20808)

* core/state/snapshot: start fixing disk iterator seek

* ethdb, rawdb, leveldb, memorydb: implement iterators with prefix and start

* les, core/state/snapshot: iterator fixes

* all: remove two iterator methods

* all: rename Iteratee.NewIteratorWith -> NewIterator

* ethdb: fix review concerns

eth/handler_test.go

@@ -317,7 +317,7 @@ func testGetNodeData(t *testing.T, protocol int) {
 	// Fetch for now the entire chain db
 	hashes := []common.Hash{}
 
-	it := db.NewIterator()
+	it := db.NewIterator(nil, nil)
 	for it.Next() {
 		if key := it.Key(); len(key) == common.HashLength {
 			hashes = append(hashes, common.BytesToHash(key))