Storage chains: indexing, renewals and reference counting (#8265)

* Transaction indexing

* Tests and fixes

* Fixed a comment

* Style

* Build

* Style

* Apply suggestions from code review

Co-authored-by: cheme <emericchevalier.pro@gmail.com>

* Code review suggestions

* Add missing impl

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* impl JoinInput

* Don't store empty slices

* JoinInput operates on slices

Co-authored-by: cheme <emericchevalier.pro@gmail.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/light/src/backend.rs

@@ -30,7 +30,7 @@ use sp_core::storage::{well_known_keys, ChildInfo};
 use sp_core::offchain::storage::InMemOffchainStorage;
 use sp_state_machine::{
 	Backend as StateBackend, TrieBackend, InMemoryBackend, ChangesTrieTransaction,
-	StorageCollection, ChildStorageCollection,
+	StorageCollection, ChildStorageCollection, IndexOperation,
 };
 use sp_runtime::{generic::BlockId, Justification, Justifications, Storage};
 use sp_runtime::traits::{Block as BlockT, NumberFor, Zero, Header, HashFor};
@@ -374,6 +374,11 @@ impl<S, Block> BlockImportOperation<Block> for ImportOperation<Block, S>
 		self.set_head = Some(block);
 		Ok(())
 	}
+
+	fn update_transaction_index(&mut self, _index: Vec<IndexOperation>) -> sp_blockchain::Result<()> {
+		// noop for the light client
+		Ok(())
+	}
 }
 
 impl<H: Hasher> std::fmt::Debug for GenesisOrUnavailableState<H> {