rpc/net: add per-peer inv_to_send sizes

test/functional/rpc_net.py

@@ -166,6 +166,7 @@ class NetTest(BitcoinTestFramework):
                 "permissions": [],
                 "presynced_headers": -1,
                 "relaytxes": False,
+                "inv_to_send": 0,
                 "services": "0000000000000000",
                 "servicesnames": [],
                 "session_id": "" if not self.options.v2transport else no_version_peer.v2_state.peer['session_id'].hex(),