Remove generic Id param from RequestId (#6032)

* rename RequestId's for better context,

and move them to lighthouse_network crate.

* remove unrequired generic AppReqId from RequestID

beacon_node/lighthouse_network/src/service/behaviour.rs

@@ -1,6 +1,6 @@
 use crate::discovery::Discovery;
 use crate::peer_manager::PeerManager;
-use crate::rpc::{ReqId, RPC};
+use crate::rpc::RPC;
 use crate::types::SnappyTransform;
 
 use libp2p::identify;
@@ -16,9 +16,8 @@ pub type SubscriptionFilter =
 pub type Gossipsub = gossipsub::Behaviour<SnappyTransform, SubscriptionFilter>;
 
 #[derive(NetworkBehaviour)]
-pub(crate) struct Behaviour<AppReqId, E>
+pub(crate) struct Behaviour<E>
 where
-    AppReqId: ReqId,
     E: EthSpec,
 {
     /// Keep track of active and pending connections to enforce hard limits.
@@ -26,7 +25,7 @@ where
     /// The peer manager that keeps track of peer's reputation and status.
     pub peer_manager: PeerManager<E>,
     /// The Eth2 RPC specified in the wire-0 protocol.
-    pub eth2_rpc: RPC<RequestId<AppReqId>, E>,
+    pub eth2_rpc: RPC<RequestId, E>,
     /// Discv5 Discovery protocol.
     pub discovery: Discovery<E>,
     /// Keep regular connection to peers and disconnect if absent.