Child trie api changes BREAKING (#4857)

Co-Authored-By: thiolliere <gui.thiolliere@gmail.com>

substrate/primitives/state-machine/src/changes_trie/input.rs

@@ -21,6 +21,7 @@ use crate::{
 	StorageKey, StorageValue,
 	changes_trie::BlockNumber
 };
+use sp_core::storage::PrefixedStorageKey;
 
 /// Key of { changed key => set of extrinsic indices } mapping.
 #[derive(Clone, Debug, PartialEq, Eq)]
@@ -49,7 +50,7 @@ pub struct ChildIndex<Number: BlockNumber> {
 	/// Block at which this key has been inserted in the trie.
 	pub block: Number,
 	/// Storage key this node is responsible for.
-	pub storage_key: StorageKey,
+	pub storage_key: PrefixedStorageKey,
 }
 
 /// Value of { changed key => block/digest block numbers } mapping.
@@ -178,7 +179,7 @@ impl<Number: BlockNumber> Decode for InputKey<Number> {
 			})),
 			3 => Ok(InputKey::ChildIndex(ChildIndex {
 				block: Decode::decode(input)?,
-				storage_key: Decode::decode(input)?,
+				storage_key: PrefixedStorageKey::new(Decode::decode(input)?),
 			})),
 			_ => Err("Invalid input key variant".into()),
 		}