BlockId removal: refactor: HeaderBackend::header (#12874)

* BlockId removal: refactor: HeaderBackend::header

It changes the arguments of:
- `HeaderBackend::header`,
- `Client::header`,
- `PeersClient::header`
- `ChainApi::block_header`

methods from: `BlockId<Block>` to: `Block::Hash`

This PR is part of BlockId::Number refactoring analysis (paritytech/substrate#11292)

* non-trivial usages of haeder(block_id) refactored

This may required introduction of dedicated function:
header_for_block_num

* fmt

* fix

* doc fixed

* ".git/.scripts/fmt.sh"

* BlockId removal: refactor: HeaderBackend::expect_header

It changes the arguments of `HeaderBackend::expect_header` method from: `BlockId<Block>` to: `Block::Hash`

* ".git/.scripts/fmt.sh"

* readme updated

* ".git/.scripts/fmt.sh"

* fix

Co-authored-by: parity-processbot <>

substrate/utils/frame/benchmarking-cli/src/storage/write.rs

@@ -21,10 +21,7 @@ use sc_client_db::{DbHash, DbState, DbStateBuilder};
 use sp_api::StateBackend;
 use sp_blockchain::HeaderBackend;
 use sp_database::{ColumnId, Transaction};
-use sp_runtime::{
-	generic::BlockId,
-	traits::{Block as BlockT, HashFor, Header as HeaderT},
-};
+use sp_runtime::traits::{Block as BlockT, HashFor, Header as HeaderT};
 use sp_trie::PrefixedMemoryDB;
 
 use log::{info, trace};
@@ -58,7 +55,7 @@ impl StorageCmd {
 		let mut record = BenchRecord::default();
 
 		let best_hash = client.usage_info().chain.best_hash;
-		let header = client.header(BlockId::Hash(best_hash))?.ok_or("Header not found")?;
+		let header = client.header(best_hash)?.ok_or("Header not found")?;
 		let original_root = *header.state_root();
 		let trie = DbStateBuilder::<Block>::new(storage.clone(), original_root).build();