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/api/src/in_mem.rs

@@ -30,7 +30,7 @@ use sp_runtime::traits::{Block as BlockT, Header as HeaderT, Zero, NumberFor, Ha
 use sp_runtime::{Justification, Justifications, Storage};
 use sp_state_machine::{
 	ChangesTrieTransaction, InMemoryBackend, Backend as StateBackend, StorageCollection,
-	ChildStorageCollection,
+	ChildStorageCollection, IndexOperation,
 };
 use sp_blockchain::{CachedHeaderMetadata, HeaderMetadata};
 
@@ -415,10 +415,10 @@ impl<Block: BlockT> blockchain::Backend<Block> for Blockchain<Block> {
 		unimplemented!()
 	}
 
-	fn extrinsic(
+	fn indexed_transaction(
 		&self,
 		_hash: &Block::Hash,
-	) -> sp_blockchain::Result<Option<<Block as BlockT>::Extrinsic>> {
+	) -> sp_blockchain::Result<Option<Vec<u8>>> {
 		unimplemented!("Not supported by the in-mem backend.")
 	}
 }
@@ -613,6 +613,10 @@ impl<Block: BlockT> backend::BlockImportOperation<Block> for BlockImportOperatio
 		self.set_head = Some(block);
 		Ok(())
 	}
+
+	fn update_transaction_index(&mut self, _index: Vec<IndexOperation>) -> sp_blockchain::Result<()> {
+		Ok(())
+	}
 }
 
 /// In-memory backend. Keeps all states and blocks in memory.