Add borsh support for PeerMessage::DistanceVector (near#9348)

In near#9187 we introduced the first new PeerMessage variant in a long time, called DistanceVector.

I got a little over-zealous about our plans to deprecate borsh and [skipped implementing borsh support for the new message variant](https://github.com/saketh-are/nearcore/blob/2093819d414bd38c73574c681715e3a544daa945/chain/network/src/network_protocol/borsh_conv.rs#L180-L182).

However, it turns out we have some test infrastructure still reliant on borsh-encoded connections:
https://github.com/near/nearcore/blob/6cdee7cc123bdeb00f0d9029b10f8c1448eab54f/pytest/lib/proxy.py#L89-L90

In particular, the nayduck test `pytest/tests/sanity/sync_chunks_from_archival.py` makes use of the proxy tool and [is failing]( https://nayduck.near.org/#/test/497500) after near#9187. 

This PR implements borsh support for DistanceVector as an immediate fix for the failing test.

In the long run we aim to deprecate borsh entirely, at which time this code (and a bunch of other code much like it) will be removed.

chain/network/src/network_protocol/borsh.rs

@@ -82,6 +82,19 @@ pub(super) struct RoutingTableUpdate {
     pub accounts: Vec<AnnounceAccount>,
 }
 
+#[derive(BorshSerialize, BorshDeserialize, PartialEq, Eq, Clone, Debug)]
+pub struct AdvertisedPeerDistance {
+    pub destination: PeerId,
+    pub distance: u32,
+}
+
+#[derive(BorshSerialize, BorshDeserialize, PartialEq, Eq, Clone, Debug)]
+pub(super) struct DistanceVector {
+    pub root: PeerId,
+    pub distances: Vec<AdvertisedPeerDistance>,
+    pub edges: Vec<Edge>,
+}
+
 #[derive(BorshSerialize, BorshDeserialize, PartialEq, Eq, Clone, Debug)]
 pub enum HandshakeFailureReason {
     ProtocolVersionMismatch { version: u32, oldest_supported_version: u32 },
@@ -139,6 +152,8 @@ pub(super) enum PeerMessage {
     _EpochSyncFinalizationRequest,
     _EpochSyncFinalizationResponse,
     _RoutingTableSyncV2,
+
+    DistanceVector(DistanceVector),
 }
 #[cfg(target_arch = "x86_64")] // Non-x86_64 doesn't match this requirement yet but it's not bad as it's not production-ready
 const _: () = assert!(std::mem::size_of::<PeerMessage>() <= 1144, "PeerMessage > 1144 bytes");

chain/network/src/network_protocol/borsh_conv.rs

@@ -90,6 +90,42 @@ impl From<mem::RoutingTableUpdate> for net::RoutingTableUpdate {
 
 //////////////////////////////////////////
 
+impl From<net::AdvertisedPeerDistance> for mem::AdvertisedPeerDistance {
+    fn from(x: net::AdvertisedPeerDistance) -> Self {
+        Self { destination: x.destination, distance: x.distance }
+    }
+}
+
+impl From<mem::AdvertisedPeerDistance> for net::AdvertisedPeerDistance {
+    fn from(x: mem::AdvertisedPeerDistance) -> Self {
+        Self { destination: x.destination, distance: x.distance }
+    }
+}
+
+//////////////////////////////////////////
+
+impl From<net::DistanceVector> for mem::DistanceVector {
+    fn from(x: net::DistanceVector) -> Self {
+        Self {
+            root: x.root,
+            distances: x.distances.into_iter().map(|y| y.into()).collect(),
+            edges: x.edges,
+        }
+    }
+}
+
+impl From<mem::DistanceVector> for net::DistanceVector {
+    fn from(x: mem::DistanceVector) -> Self {
+        Self {
+            root: x.root,
+            distances: x.distances.into_iter().map(|y| y.into()).collect(),
+            edges: x.edges,
+        }
+    }
+}
+
+//////////////////////////////////////////
+
 #[derive(thiserror::Error, Debug)]
 pub enum ParsePeerMessageError {
     #[error("HandshakeV2 is deprecated")]
@@ -156,6 +192,7 @@ impl TryFrom<&net::PeerMessage> for mem::PeerMessage {
             net::PeerMessage::_RoutingTableSyncV2 => {
                 return Err(Self::Error::DeprecatedRoutingTableSyncV2)
             }
+            net::PeerMessage::DistanceVector(dv) => mem::PeerMessage::DistanceVector(dv.into()),
         })
     }
 }
@@ -177,9 +214,7 @@ impl From<&mem::PeerMessage> for net::PeerMessage {
                 net::PeerMessage::SyncRoutingTable(rtu.into())
             }
             mem::PeerMessage::RequestUpdateNonce(e) => net::PeerMessage::RequestUpdateNonce(e),
-            mem::PeerMessage::DistanceVector(_) => {
-                panic!("DistanceVector is not supported in Borsh encoding")
-            }
+            mem::PeerMessage::DistanceVector(dv) => net::PeerMessage::DistanceVector(dv.into()),
 
             // This message is not supported, we translate it to an empty RoutingTableUpdate.
             mem::PeerMessage::SyncAccountsData(_) => {