Prepare separation of event loop initialisation to swap initialisation

As for Alice, the event loop will be started with the program and will
be the one starting swaps (`run_until`) based on libp2p events (swap
request).

swap/src/protocol/alice.rs

@@ -7,7 +7,6 @@ use crate::{
     monero,
     network::{
         peer_tracker::{self, PeerTracker},
-        transport::build,
         Seed as NetworkSeed,
     },
     protocol::{bob::EncryptedSignature, SwapAmounts},
@@ -113,7 +112,8 @@ impl Builder {
                     .make_initial_state(swap_amounts.btc, swap_amounts.xmr)
                     .await?;
 
-                let (event_loop, event_loop_handle) = self.init_event_loop()?;
+                let (event_loop, event_loop_handle) =
+                    EventLoop::new(self.identity.clone(), self.listen_address(), self.peer_id)?;
 
                 Ok((
                     Swap {
@@ -139,7 +139,8 @@ impl Builder {
                         )
                     };
 
-                let (event_loop, event_loop_handle) = self.init_event_loop()?;
+                let (event_loop, event_loop_handle) =
+                    EventLoop::new(self.identity.clone(), self.listen_address(), self.peer_id)?;
 
                 Ok((
                     Swap {
@@ -186,17 +187,6 @@ impl Builder {
 
         Ok(AliceState::Started { amounts, state0 })
     }
-
-    fn init_event_loop(&self) -> Result<(EventLoop, EventLoopHandle)> {
-        let alice_behaviour = Behaviour::default();
-        let alice_transport = build(self.identity.clone())?;
-        EventLoop::new(
-            alice_transport,
-            alice_behaviour,
-            self.listen_address(),
-            self.peer_id,
-        )
-    }
 }
 
 #[derive(Debug)]

swap/src/protocol/alice/event_loop.rs

@@ -1,6 +1,6 @@
 use crate::{
     execution_params::ExecutionParams,
-    network::{transport::SwapTransport, TokioExecutor},
+    network::{transport, TokioExecutor},
     protocol::{
         alice::{Behaviour, OutEvent, State0, State3, SwapResponse, TransferProof},
         bob::{EncryptedSignature, SwapRequest},
@@ -135,11 +135,13 @@ pub struct EventLoop {
 
 impl EventLoop {
     pub fn new(
-        transport: SwapTransport,
-        behaviour: Behaviour,
+        identity: libp2p::identity::Keypair,
         listen: Multiaddr,
         peer_id: PeerId,
     ) -> Result<(Self, EventLoopHandle)> {
+        let behaviour = Behaviour::default();
+        let transport = transport::build(identity)?;
+
         let mut swarm = libp2p::swarm::SwarmBuilder::new(transport, behaviour, peer_id)
             .executor(Box::new(TokioExecutor {
                 handle: tokio::runtime::Handle::current(),