ed25519_verify: Support using dalek for historical blocks (#12661)

* ed25519_verify: Support using dalek for historical blocks

The switch from `ed25519-dalek` to `ed25519-zebra` was actually a breaking change. `ed25519-zebra`
is more permissive. To support historical blocks when syncing a chain this pull request introduces
an externalities extension `UseDalekExt`. This extension is just used as a signaling mechanism to
`ed25519_verify` to use `ed25519-dalek` when it is present. Together with `ExtensionBeforeBlock` it
can be used to setup a node in way to sync historical blocks that require `ed25519-dalek`, because
they included a transaction that verified differently as when using `ed25519-zebra`.

This feature can be enabled in the following way. In the chain service file, directly after the
client is created, the following code should be added:

```
use sc_client_api::ExecutorProvider;
client.execution_extensions().set_extensions_factory(
	sc_client_api::execution_extensions::ExtensionBeforeBlock::<Block, sp_io::UseDalekExt>::new(BLOCK_NUMBER_UNTIL_DALEK_SHOULD_BE_USED)
);
```

* Fix doc

* More fixes

* Update client/api/src/execution_extensions.rs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

* Fix merge and warning

* Fix docs

Co-authored-by: André Silva <123550+andresilva@users.noreply.github.com>

substrate/primitives/state-machine/src/lib.rs

@@ -532,6 +532,7 @@ mod execution {
 			method,
 			call_data,
 			runtime_code,
+			Default::default(),
 		)
 	}
 
@@ -552,6 +553,7 @@ mod execution {
 		method: &str,
 		call_data: &[u8],
 		runtime_code: &RuntimeCode,
+		extensions: Extensions,
 	) -> Result<(Vec<u8>, StorageProof), Box<dyn Error>>
 	where
 		S: trie_backend_essence::TrieBackendStorage<H>,
@@ -569,7 +571,7 @@ mod execution {
 			exec,
 			method,
 			call_data,
-			Extensions::default(),
+			extensions,
 			runtime_code,
 			spawn_handle,
 		)