bench pallet: only require Hash instead of Block (#3244)

Preparation for https://github.com/paritytech/polkadot-sdk/issues/2664

Changes:
- Only require `Hash` instead of `Block` for the benchmarking
- Refactor DB types to do the same

## Integration

This breaking change can easily be integrated into your node via:  
```patch
- cmd.run::<Block, ()>(config)
+ cmd.run::<HashingFor<Block>, ()>(config)
```

Status: waiting for CI checks

---------

Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: cheme <emericchevalier.pro@gmail.com>

substrate/bin/node-template/node/src/command.rs

@@ -117,7 +117,7 @@ pub fn run() -> sc_cli::Result<()> {
 							)
 						}
 
-						cmd.run::<Block, ()>(config)
+						cmd.run::<sp_runtime::traits::HashingFor<Block>, ()>(config)
 					},
 					BenchmarkCmd::Block(cmd) => {
 						let PartialComponents { client, .. } = service::new_partial(&config)?;