Self rate limiting dev flag (#3928)

## Issue Addressed
Adds self rate limiting options, mainly with the idea to comply with peer's rate limits in small testnets

## Proposed Changes
Add a hidden flag `self-limiter` this can take no value, or customs values to configure quotas per protocol

## Additional Info
### How to use
`--self-limiter` will turn on the self rate limiter applying the same params we apply to inbound requests (requests from other peers)
`--self-limiter "beacon_blocks_by_range:64/1"` will turn on the self rate limiter for ALL protocols, but change the quota for bbrange to 64 requested blocks per 1 second.
`--self-limiter "beacon_blocks_by_range:64/1;ping:1/10"` same as previous one, changing the quota for ping as well.

### Caveats
- The rate limiter is either on or off for all protocols. I added the custom values to be able to change the quotas per protocol so that some protocols can be given extremely loose or tight quotas. I think this should satisfy every need even if we can't technically turn off rate limits per protocol.
- This reuses the rate limiter struct for the inbound requests so there is this ugly part of the code in which we need to deal with the inbound only protocols (light client stuff) if this becomes too ugly as we add lc protocols, we might want to split the rate limiters. I've checked this and looks doable with const generics to avoid so much code duplication

### Knowing if this is on
```
Feb 06 21:12:05.493 DEBG Using self rate limiting params         config: OutboundRateLimiterConfig { ping: 2/10s, metadata: 1/15s, status: 5/15s, goodbye: 1/10s, blocks_by_range: 1024/10s, blocks_by_root: 128/10s }, service: libp2p_rpc, service: libp2p
```

beacon_node/lighthouse_network/src/rpc/mod.rs

@@ -12,7 +12,7 @@ use libp2p::swarm::{
     PollParameters, SubstreamProtocol,
 };
 use libp2p::PeerId;
-use rate_limiter::{RPCRateLimiter as RateLimiter, RPCRateLimiterBuilder, RateLimitedErr};
+use rate_limiter::{RPCRateLimiter as RateLimiter, RateLimitedErr};
 use slog::{crit, debug, o};
 use std::marker::PhantomData;
 use std::sync::Arc;
@@ -32,12 +32,17 @@ pub use methods::{
 pub(crate) use outbound::OutboundRequest;
 pub use protocol::{max_rpc_size, Protocol, RPCError};
 
+use self::config::OutboundRateLimiterConfig;
+use self::self_limiter::SelfRateLimiter;
+
 pub(crate) mod codec;
+pub mod config;
 mod handler;
 pub mod methods;
 mod outbound;
 mod protocol;
 mod rate_limiter;
+mod self_limiter;
 
 /// Composite trait for a request id.
 pub trait ReqId: Send + 'static + std::fmt::Debug + Copy + Clone {}
@@ -100,13 +105,18 @@ pub struct RPCMessage<Id, TSpec: EthSpec> {
     pub event: HandlerEvent<Id, TSpec>,
 }
 
+type BehaviourAction<Id, TSpec> =
+    NetworkBehaviourAction<RPCMessage<Id, TSpec>, RPCHandler<Id, TSpec>>;
+
 /// Implements the libp2p `NetworkBehaviour` trait and therefore manages network-level
 /// logic.
 pub struct RPC<Id: ReqId, TSpec: EthSpec> {
     /// Rate limiter
     limiter: RateLimiter,
+    /// Rate limiter for our own requests.
+    self_limiter: Option<SelfRateLimiter<Id, TSpec>>,
     /// Queue of events to be processed.
-    events: Vec<NetworkBehaviourAction<RPCMessage<Id, TSpec>, RPCHandler<Id, TSpec>>>,
+    events: Vec<BehaviourAction<Id, TSpec>>,
     fork_context: Arc<ForkContext>,
     enable_light_client_server: bool,
     /// Slog logger for RPC behaviour.
@@ -117,10 +127,12 @@ impl<Id: ReqId, TSpec: EthSpec> RPC<Id, TSpec> {
     pub fn new(
         fork_context: Arc<ForkContext>,
         enable_light_client_server: bool,
+        outbound_rate_limiter_config: Option<OutboundRateLimiterConfig>,
         log: slog::Logger,
     ) -> Self {
         let log = log.new(o!("service" => "libp2p_rpc"));
-        let limiter = RPCRateLimiterBuilder::new()
+
+        let limiter = RateLimiter::builder()
             .n_every(Protocol::MetaData, 2, Duration::from_secs(5))
             .n_every(Protocol::Ping, 2, Duration::from_secs(10))
             .n_every(Protocol::Status, 5, Duration::from_secs(15))
@@ -134,8 +146,14 @@ impl<Id: ReqId, TSpec: EthSpec> RPC<Id, TSpec> {
             .n_every(Protocol::BlocksByRoot, 128, Duration::from_secs(10))
             .build()
             .expect("Configuration parameters are valid");
+
+        let self_limiter = outbound_rate_limiter_config.map(|config| {
+            SelfRateLimiter::new(config, log.clone()).expect("Configuration parameters are valid")
+        });
+
         RPC {
             limiter,
+            self_limiter,
             events: Vec::new(),
             fork_context,
             enable_light_client_server,
@@ -162,12 +180,24 @@ impl<Id: ReqId, TSpec: EthSpec> RPC<Id, TSpec> {
     /// Submits an RPC request.
     ///
     /// The peer must be connected for this to succeed.
-    pub fn send_request(&mut self, peer_id: PeerId, request_id: Id, event: OutboundRequest<TSpec>) {
-        self.events.push(NetworkBehaviourAction::NotifyHandler {
-            peer_id,
-            handler: NotifyHandler::Any,
-            event: RPCSend::Request(request_id, event),
-        });
+    pub fn send_request(&mut self, peer_id: PeerId, request_id: Id, req: OutboundRequest<TSpec>) {
+        let event = if let Some(self_limiter) = self.self_limiter.as_mut() {
+            match self_limiter.allows(peer_id, request_id, req) {
+                Ok(event) => event,
+                Err(_e) => {
+                    // Request is logged and queued internally in the self rate limiter.
+                    return;
+                }
+            }
+        } else {
+            NetworkBehaviourAction::NotifyHandler {
+                peer_id,
+                handler: NotifyHandler::Any,
+                event: RPCSend::Request(request_id, req),
+            }
+        };
+
+        self.events.push(event);
     }
 
     /// Lighthouse wishes to disconnect from this peer by sending a Goodbye message. This
@@ -272,11 +302,19 @@ where
         cx: &mut Context,
         _: &mut impl PollParameters,
     ) -> Poll<NetworkBehaviourAction<Self::OutEvent, Self::ConnectionHandler>> {
-        // let the rate limiter prune
+        // let the rate limiter prune.
         let _ = self.limiter.poll_unpin(cx);
+
+        if let Some(self_limiter) = self.self_limiter.as_mut() {
+            if let Poll::Ready(event) = self_limiter.poll_ready(cx) {
+                self.events.push(event)
+            }
+        }
+
         if !self.events.is_empty() {
             return Poll::Ready(self.events.remove(0));
         }
+
         Poll::Pending
     }
 }