RPC RequestId Cleanup (#7238)

I've been working at updating another library to latest Lighthouse and got very confused with RPC request Ids.

There were types that had fields called `request_id` and `id`. And interchangeably could have types `PeerRequestId`, `rpc::RequestId`, `AppRequestId`, `api_types::RequestId` or even `Request.id`.

I couldn't keep track of which Id was linked to what and what each type meant.

So this PR mainly does a few things:
- Changes the field naming to match the actual type. So any field that has an  `AppRequestId` will be named `app_request_id` rather than `id` or `request_id` for example.
- I simplified the types. I removed the two different `RequestId` types (one in Lighthouse_network the other in the rpc) and grouped them into one. It has one downside tho. I had to add a few unreachable lines of code in the beacon processor, which the extra type would prevent, but I feel like it might be worth it. Happy to add an extra type to avoid those few lines.
- I also removed the concept of `PeerRequestId` which sometimes went alongside a `request_id`. There were times were had a `PeerRequest` and a `Request` being returned, both of which contain a `RequestId` so we had redundant information. I've simplified the logic by removing `PeerRequestId` and made a `ResponseId`. I think if you look at the code changes, it simplifies things a bit and removes the redundant extra info.

I think with this PR things are a little bit easier to reasonable about what is going on with all these RPC Ids.

NOTE: I did this with the help of AI, so probably should be checked

beacon_node/network/src/sync/network_context.rs

@@ -372,11 +372,11 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
             );
 
             let request = RequestType::Status(status_message.clone());
-            let request_id = AppRequestId::Router;
+            let app_request_id = AppRequestId::Router;
             let _ = self.send_network_msg(NetworkMessage::SendRequest {
                 peer_id,
                 request,
-                request_id,
+                app_request_id,
             });
         }
     }
@@ -595,7 +595,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
             .send(NetworkMessage::SendRequest {
                 peer_id,
                 request: RequestType::BlocksByRoot(request.into_request(&self.fork_context)),
-                request_id: AppRequestId::Sync(SyncRequestId::SingleBlock { id }),
+                app_request_id: AppRequestId::Sync(SyncRequestId::SingleBlock { id }),
             })
             .map_err(|_| RpcRequestSendError::NetworkSendError)?;
 
@@ -684,7 +684,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
             .send(NetworkMessage::SendRequest {
                 peer_id,
                 request: RequestType::BlobsByRoot(request.clone().into_request(&self.fork_context)),
-                request_id: AppRequestId::Sync(SyncRequestId::SingleBlob { id }),
+                app_request_id: AppRequestId::Sync(SyncRequestId::SingleBlob { id }),
             })
             .map_err(|_| RpcRequestSendError::NetworkSendError)?;
 
@@ -733,7 +733,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
         self.send_network_msg(NetworkMessage::SendRequest {
             peer_id,
             request: RequestType::DataColumnsByRoot(request.clone().into_request(&self.chain.spec)),
-            request_id: AppRequestId::Sync(SyncRequestId::DataColumnsByRoot(id)),
+            app_request_id: AppRequestId::Sync(SyncRequestId::DataColumnsByRoot(id)),
         })?;
 
         debug!(
@@ -839,7 +839,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
             .send(NetworkMessage::SendRequest {
                 peer_id,
                 request: RequestType::BlocksByRange(request.clone().into()),
-                request_id: AppRequestId::Sync(SyncRequestId::BlocksByRange(id)),
+                app_request_id: AppRequestId::Sync(SyncRequestId::BlocksByRange(id)),
             })
             .map_err(|_| RpcRequestSendError::NetworkSendError)?;
 
@@ -880,7 +880,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
             .send(NetworkMessage::SendRequest {
                 peer_id,
                 request: RequestType::BlobsByRange(request.clone()),
-                request_id: AppRequestId::Sync(SyncRequestId::BlobsByRange(id)),
+                app_request_id: AppRequestId::Sync(SyncRequestId::BlobsByRange(id)),
             })
             .map_err(|_| RpcRequestSendError::NetworkSendError)?;
 
@@ -919,7 +919,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
         self.send_network_msg(NetworkMessage::SendRequest {
             peer_id,
             request: RequestType::DataColumnsByRange(request.clone()),
-            request_id: AppRequestId::Sync(SyncRequestId::DataColumnsByRange(id)),
+            app_request_id: AppRequestId::Sync(SyncRequestId::DataColumnsByRange(id)),
         })
         .map_err(|_| RpcRequestSendError::NetworkSendError)?;