Integrate session pallet into validator-sets pallet (#440)

* remove pallet-session

* Store key shares in InSet

* integrate grandpa to vs-pallet

* integrate pallet babe

* remove pallet-session & authority discovery from runtime

* update the grandpa pallet path

* cargo update grandpa

* cargo update substrate

* Misc tweaks

Sets validators for BABE/GRANDPA in chain_spec, per Akil's realization that was
the missing piece.

* fix pr comments

* bug fix & tidy up

---------

Co-authored-by: Luke Parker <lukeparker5132@gmail.com>

substrate/client/src/serai/validator_sets.rs

@@ -44,7 +44,10 @@ impl<'a> SeraiValidatorSets<'a> {
     self.0.storage(PALLET, "CurrentSession", Some(vec![scale_value(network)])).await
   }
 
-  pub async fn participants(&self, network: NetworkId) -> Result<Option<Vec<Public>>, SeraiError> {
+  pub async fn participants(
+    &self,
+    network: NetworkId,
+  ) -> Result<Option<Vec<(Public, u64)>>, SeraiError> {
     self.0.storage(PALLET, "Participants", Some(vec![scale_value(network)])).await
   }