Infrastructure improvements (#2897)

* Factor out runtime module into utils.

* Add maybe_authority information to `PeerConnected` event.

We already gather this information in authority discovery, so we might
as well share it with others.

This opens up an easy path to trigger validators differently from normal
nodes, e.g. for prioritization. This change has become more important
now, that we just connect to all validators and therefore just have a
long peer list without any information about those nodes.

* Test fix.

polkadot/node/network/availability-distribution/src/error.rs

@@ -18,12 +18,15 @@
 //! Error handling related code and Error/Result definitions.
 
 use polkadot_node_network_protocol::request_response::request::RequestError;
+use polkadot_primitives::v1::SessionIndex;
 use thiserror::Error;
 
 use futures::channel::oneshot;
 
-use polkadot_node_subsystem_util::Error as UtilError;
-use polkadot_primitives::v1::SessionIndex;
+use polkadot_node_subsystem_util::{
+	runtime,
+	Error as UtilError,
+};
 use polkadot_subsystem::{errors::RuntimeApiError, SubsystemError};
 
 use crate::LOG_TARGET;
@@ -74,10 +77,6 @@ pub enum Error {
 	#[error("Runtime API error")]
 	RuntimeRequest(RuntimeApiError),
 
-	/// We tried fetching a session info which was not available.
-	#[error("There was no session with the given index")]
-	NoSuchSession(SessionIndex),
-
 	/// Fetching PoV failed with `RequestError`.
 	#[error("FetchPoV request error")]
 	FetchPoV(#[source] RequestError),
@@ -92,10 +91,24 @@ pub enum Error {
 	/// No validator with the index could be found in current session.
 	#[error("Given validator index could not be found")]
 	InvalidValidatorIndex,
+
+	/// We tried fetching a session info which was not available.
+	#[error("There was no session with the given index")]
+	NoSuchSession(SessionIndex),
+
+	/// Errors coming from runtime::Runtime.
+	#[error("Error while accessing runtime information")]
+	Runtime(#[source] runtime::Error),
 }
 
 pub type Result<T> = std::result::Result<T, Error>;
 
+impl From<runtime::Error> for Error {
+	fn from(err: runtime::Error) -> Self {
+		Self::Runtime(err)
+	}
+}
+
 impl From<SubsystemError> for Error {
 	fn from(err: SubsystemError) -> Self {
 		Self::IncomingMessageChannel(err)