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>

prdoc/pr_3244.prdoc

@@ -0,0 +1,18 @@
+title: "Make the `benchmark pallet` command only require a Hasher"
+
+doc:
+  - audience: Node Dev
+    description: |
+      Currently the `benchmark pallet` command requires a `Block` type, while only using its hasher.
+      Now this is changed to only require the hasher. This means to use `HashingFor<Block>` in the
+      place where `Block` was required.  
+      Example patch for your node with `cmd` being `BenchmarkCmd::Pallet(cmd)`:
+
+      ```patch
+      - cmd.run::<Block, ()>(config)
+      + cmd.run::<HashingFor<Block>, ()>(config)
+      ```
+
+crates:
+  - name: sc-client-db
+  - name: frame-benchmarking-cli