[offchain] Support for sign & verify for crypto keys (#3023)

* Implement sign & verify.

* Use phrases and password.

* Sign & verify with authority keys.

* Fix tests.

* WiP

* WiP

* Allow the caller to decide on 'CryptoKind'.

* Remove TODO.

* Make seed private back.

* Fix non-std build and bump version.

* Use Into<u32> instead of asses.

* Add missing typedef.

substrate/core/cli/src/lib.rs

@@ -376,7 +376,7 @@ where
 	let spec = load_spec(&cli.shared_params, spec_factory)?;
 	let mut config = service::Configuration::default_with_spec(spec.clone());
 	if cli.interactive_password {
-		config.password = input_keystore_password()?
+		config.password = input_keystore_password()?.into()
 	}
 
 	config.impl_name = impl_name;