Add assignment keys to session keys, no separate approvals key (#2092)

* guide: merge backing and approval keys

* bump substrate master & update primitives

* use new SessionInfo struct in session_info

* session keys upgrade for Polkadot

* kusama & westend runtimes

* bump westend, kusama, and polkadot versions

* add session key to rococo & test-runtime

* update prepare-test-net to latest subkey

* update chain specs to support new para_assignment session key

* get cargo.lock from master

* formatting

* update kill_storage based on substrate master

* fix test-service

* assgn -> asgn

* use session info module for assignment session key

polkadot/runtime/common/src/lib.rs

@@ -27,7 +27,7 @@ pub mod impls;
 pub mod paras_sudo_wrapper;
 pub mod paras_registrar;
 
-use primitives::v1::{BlockNumber, ValidatorId};
+use primitives::v1::{BlockNumber, ValidatorId, AssignmentId};
 use sp_runtime::{Perquintill, Perbill, FixedPointNumber};
 use frame_system::limits;
 use frame_support::{
@@ -158,6 +158,35 @@ impl<T: pallet_session::Config>
 	fn on_disabled(_: usize) { }
 }
 
+/// A placeholder since there is currently no provided session key handler for parachain validator
+/// keys.
+pub struct AssignmentSessionKeyPlaceholder<T>(sp_std::marker::PhantomData<T>);
+impl<T> sp_runtime::BoundToRuntimeAppPublic for AssignmentSessionKeyPlaceholder<T> {
+	type Public = AssignmentId;
+}
+
+impl<T: pallet_session::Config>
+	pallet_session::OneSessionHandler<T::AccountId> for AssignmentSessionKeyPlaceholder<T>
+{
+	type Key = AssignmentId;
+
+	fn on_genesis_session<'a, I: 'a>(_validators: I) where
+		I: Iterator<Item = (&'a T::AccountId, AssignmentId)>,
+		T::AccountId: 'a
+	{
+
+	}
+
+	fn on_new_session<'a, I: 'a>(_changed: bool, _v: I, _q: I) where
+		I: Iterator<Item = (&'a T::AccountId, AssignmentId)>,
+		T::AccountId: 'a
+	{
+
+	}
+
+	fn on_disabled(_: usize) { }
+}
+
 #[cfg(test)]
 mod multiplier_tests {
 	use super::*;