Fix benchmark read/write key tracker for keys in child storages. (#6905)

* WIP: read child trie and write child trie

* add test

* refactor a bit + improve log

* better naming

* trigger CI

* Revert "trigger CI"

This reverts commit d0aadaeb6a12fc6c39f01b3c1b5725d19f085865.

substrate/primitives/state-machine/src/backend.rs

@@ -26,7 +26,7 @@ use sp_core::{
 use crate::{
 	trie_backend::TrieBackend,
 	trie_backend_essence::TrieBackendStorage,
-	UsageInfo, StorageKey, StorageValue, StorageCollection,
+	UsageInfo, StorageKey, StorageValue, StorageCollection, ChildStorageCollection,
 };
 
 /// A state backend is used to read state data and can have changes committed
@@ -215,7 +215,13 @@ pub trait Backend<H: Hasher>: std::fmt::Debug {
 	}
 
 	/// Commit given transaction to storage.
-	fn commit(&self, _: H::Out, _: Self::Transaction, _: StorageCollection) -> Result<(), Self::Error> {
+	fn commit(
+		&self,
+		_: H::Out,
+		_: Self::Transaction,
+		_: StorageCollection,
+		_: ChildStorageCollection,
+	) -> Result<(), Self::Error> {
 		unimplemented!()
 	}
 

substrate/primitives/state-machine/src/ext.rs

@@ -594,6 +594,7 @@ where
 			changes.transaction_storage_root,
 			changes.transaction,
 			changes.main_storage_changes,
+			changes.child_storage_changes,
 		).expect(EXT_NOT_ALLOWED_TO_FAIL);
 		self.mark_dirty();
 		self.overlay