Manually insert the authority discovery key into the keystore

I did try pulling in `pallet-authority-discovery` for this, updating
`SessionKeys`, but that was insufficient for whatever reason.

substrate/client/src/serai/mod.rs

@@ -315,7 +315,7 @@ impl Serai {
     &self,
     network: NetworkId,
   ) -> Result<Vec<multiaddr::Multiaddr>, SeraiError> {
-    self.call("p2p_validators", network).await
+    self.call("p2p_validators", [network]).await
   }
 }
 

substrate/node/src/rpc.rs

@@ -59,7 +59,7 @@ where
     authority_discovery_module.register_async_method(
       "p2p_validators",
       |params, context, _ext| async move {
-        let network: NetworkId = params.parse()?;
+        let [network]: [NetworkId; 1] = params.parse()?;
         let (id, client, authority_discovery) = &*context;
         let latest_block = client.info().best_hash;
 

substrate/node/src/service.rs

@@ -287,6 +287,9 @@ pub fn new_full(mut config: Configuration) -> Result<TaskManager, ServiceError>
 
   let role = config.role;
   let keystore = keystore_container;
+  if let Some(seed) = config.dev_key_seed.as_ref() {
+    let _ = keystore.sr25519_generate_new(sp_core::crypto::key_types::AUTHORITY_DISCOVERY, Some(seed));
+  }
   let prometheus_registry = config.prometheus_registry().cloned();
 
   // TODO: Ensure we're considered as an authority is a validator of an external network