Add Keccak hasher (#6101)

* fix keccak hasher

* Update hasher.rs

Co-authored-by: Gavin Wood <i@gavwood.com>

substrate/primitives/io/src/lib.rs

@@ -300,6 +300,16 @@ pub trait Trie {
 	fn blake2_256_ordered_root(input: Vec<Vec<u8>>) -> H256 {
 		Layout::<sp_core::Blake2Hasher>::ordered_trie_root(input)
 	}
+
+	/// A trie root formed from the iterated items.
+	fn keccak_256_root(input: Vec<(Vec<u8>, Vec<u8>)>) -> H256 {
+		Layout::<sp_core::KeccakHasher>::trie_root(input)
+	}
+
+	/// A trie root formed from the enumerated items.
+	fn keccak_256_ordered_root(input: Vec<Vec<u8>>) -> H256 {
+		Layout::<sp_core::KeccakHasher>::ordered_trie_root(input)
+	}
 }
 
 /// Interface that provides miscellaneous functions for communicating between the runtime and the node.