Prepare for network protocol version upgrades (#5084)

* explicitly tag network requests with version

* fmt

* make PeerSet more aware of versioning

* some generalization of the network bridge to support upgrades

* walk back some renaming

* walk back some version stuff

* extract version from fallback

* remove V1 from NetworkBridgeUpdate

* add accidentally-removed timer

* implement focusing for versioned messages

* fmt

* fix up network bridge & tests

* remove inaccurate version check in bridge

* remove some TODO [now]s

* fix fallout in statement distribution

* fmt

* fallout in gossip-support

* fix fallout in collator-protocol

* fix fallout in bitfield-distribution

* fix fallout in approval-distribution

* fmt

* use never!

* fmt

polkadot/node/network/availability-recovery/src/tests.rs

@@ -292,7 +292,7 @@ impl TestState {
 						i += 1;
 						assert_matches!(
 							req,
-							Requests::ChunkFetching(req) => {
+							Requests::ChunkFetchingV1(req) => {
 								assert_eq!(req.payload.candidate_hash, candidate_hash);
 
 								let validator_index = req.payload.index.0 as usize;
@@ -341,7 +341,7 @@ impl TestState {
 
 					assert_matches!(
 						requests.pop().unwrap(),
-						Requests::AvailableDataFetching(req) => {
+						Requests::AvailableDataFetchingV1(req) => {
 							assert_eq!(req.payload.candidate_hash, candidate_hash);
 							let validator_index = self.validator_authority_id
 								.iter()