Request based collation fetching (#2621)

* Introduce collation fetching protocol

also move to mod.rs

* Allow `PeerId`s in requests to network bridge.

* Fix availability distribution tests.

* Move CompressedPoV to primitives.

* Request based collator protocol: validator side

- Missing: tests
- Collator side
- don't connect, if not connected

* Fixes.

* Basic request based collator side.

* Minor fix on collator side.

* Don't connect in requests in collation protocol.

Also some cleanup.

* Fix PoV distribution

* Bump substrate

* Add back metrics + whitespace fixes.

* Add back missing spans.

* More cleanup.

* Guide update.

* Fix tests

* Handle results in tests.

* Fix weird compilation issue.

* Add missing )

* Get rid of dead code.

* Get rid of redundant import.

* Fix runtime build.

* Cleanup.

* Fix wasm build.

* Format fixes.

Thanks @andronik !

polkadot/node/network/availability-distribution/src/tests/state.rs

@@ -29,6 +29,7 @@ use sp_keystore::{SyncCryptoStore, SyncCryptoStorePtr};
 use sp_keyring::Sr25519Keyring;
 use sp_core::{traits::SpawnNamed, testing::TaskExecutor};
 use sc_network as network;
+use sc_network::IfDisconnected;
 use sc_network::config as netconfig;
 
 use polkadot_subsystem::{ActiveLeavesUpdate, FromOverseer, OverseerSignal, messages::{AllMessages,
@@ -201,7 +202,7 @@ impl TestState {
 			tracing::trace!(target: LOG_TARGET, remaining_stores, "Stores left to go");
 			let msg = overseer_recv(&mut rx).await;
 			match msg {
-				AllMessages::NetworkBridge(NetworkBridgeMessage::SendRequests(reqs)) => {
+				AllMessages::NetworkBridge(NetworkBridgeMessage::SendRequests(reqs, IfDisconnected::TryConnect)) => {
 					for req in reqs {
 						// Forward requests:
 						let in_req = to_incoming_req(&executor, req);
@@ -313,5 +314,6 @@ fn to_incoming_req(
 				tx
 			)
 		}
+		_ => panic!("Unexpected request!"),
 	}
 }