Deduplicate pallet call structs used for indirect runtime calls (#1744)

* Small changes

* Define generic bridge pallets call structs

* polkadot-core SignedExtension simplifications

- we don't seem to need to pass the Call as a generic param
- we can use codec(skip) instead of implementing Encode and Decode

* Split BridgeHubRococo and BridgeHubWococo calls

* code review fixes

bridges/primitives/runtime/src/calls.rs

@@ -0,0 +1,30 @@
+// Copyright 2019-2023 Parity Technologies (UK) Ltd.
+// This file is part of Parity Bridges Common.
+
+// Parity Bridges Common is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity Bridges Common is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity Bridges Common.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Basic runtime calls.
+
+use codec::{Decode, Encode};
+use scale_info::TypeInfo;
+use sp_std::vec::Vec;
+
+/// A minimized version of `frame-system::Call` that can be used without a runtime.
+#[derive(Encode, Decode, Debug, PartialEq, Eq, Clone, TypeInfo)]
+#[allow(non_camel_case_types)]
+pub enum SystemCall {
+	/// `frame-system::Call::remark`
+	#[codec(index = 1)]
+	remark(Vec<u8>),
+}

bridges/primitives/runtime/src/lib.rs

@@ -47,6 +47,7 @@ pub use storage_types::BoundedStorageValue;
 #[cfg(feature = "std")]
 pub use storage_proof::craft_valid_storage_proof;
 
+pub mod calls;
 pub mod messages;
 
 mod chain;