split NetworkBridge into two subsystems (#5616)

* foo

* rolling session window

* fixup

* remove use statemetn

* fmt

* split NetworkBridge into two subsystems

Pending cleanup

* split

* chore: reexport OrchestraError as OverseerError

* chore: silence warnings

* fixup tests

* chore: add default timenout of 30s to subsystem test helper ctx handle

* single item channel

* fixins

* fmt

* cleanup

* remove dead code

* remove sync bounds again

* wire up shared state

* deal with some FIXMEs

* use distinct tags

Co-authored-by: Andrei Sandu <54316454+sandreim@users.noreply.github.com>

* use tag

Co-authored-by: Andrei Sandu <54316454+sandreim@users.noreply.github.com>

* address naming

tx and rx are common in networking and also have an implicit meaning regarding networking
compared to incoming and outgoing which are already used with subsystems themselvesq

* remove unused sync oracle

* remove unneeded state

* fix tests

* chore: fmt

* do not try to register twice

* leak Metrics type

Co-authored-by: Andrei Sandu <54316454+sandreim@users.noreply.github.com>
Co-authored-by: Andronik <write@reusable.software>

polkadot/node/network/bridge/src/errors.rs

@@ -0,0 +1,20 @@
+use polkadot_node_subsystem::SubsystemError;
+pub(crate) use polkadot_overseer::OverseerError;
+
+#[fatality::fatality(splitable)]
+pub(crate) enum Error {
+	/// Received error from overseer:
+	#[fatal]
+	#[error(transparent)]
+	SubsystemError(#[from] SubsystemError),
+	/// The stream of incoming events concluded.
+	#[fatal]
+	#[error("Event stream closed unexpectedly")]
+	EventStreamConcluded,
+}
+
+impl From<OverseerError> for Error {
+	fn from(e: OverseerError) -> Self {
+		Error::SubsystemError(SubsystemError::from(e))
+	}
+}