feat: replace ProtocolName with AsRef<str>

Previously, a protocol could be any sequence of bytes as long as it started with `/`. Now, we directly parse a protocol as `String` which enforces it to be valid UTF8.

To notify users of this change, we delete the `ProtocolName` trait. The new requirement is that users need to provide a type that implements `AsRef<str>`.

We also add a `StreamProtocol` newtype in `libp2p-swarm` which provides an easy way for users to ensure their protocol strings are compliant. The newtype enforces that protocol strings start with `/`. `StreamProtocol` also implements `AsRef<str>`, meaning users can directly use it in their upgrades.

`multistream-select` by itself only changes marginally with this patch. The only thing we enforce in the type-system is that protocols must implement `AsRef<str>`.

Resolves: #2831.

Pull-Request: #3746.

protocols/gossipsub/src/behaviour.rs

@@ -52,7 +52,7 @@ use crate::handler::{Handler, HandlerEvent, HandlerIn};
 use crate::mcache::MessageCache;
 use crate::metrics::{Churn, Config as MetricsConfig, Inclusion, Metrics, Penalty};
 use crate::peer_score::{PeerScore, PeerScoreParams, PeerScoreThresholds, RejectReason};
-use crate::protocol::{ProtocolConfig, SIGNING_PREFIX};
+use crate::protocol::SIGNING_PREFIX;
 use crate::subscription_filter::{AllowAllSubscriptionFilter, TopicSubscriptionFilter};
 use crate::time_cache::{DuplicateCache, TimeCache};
 use crate::topic::{Hasher, Topic, TopicHash};
@@ -3317,7 +3317,7 @@ where
         _: &Multiaddr,
     ) -> Result<THandler<Self>, ConnectionDenied> {
         Ok(Handler::new(
-            ProtocolConfig::new(&self.config),
+            self.config.protocol_config(),
             self.config.idle_timeout(),
         ))
     }
@@ -3330,7 +3330,7 @@ where
         _: Endpoint,
     ) -> Result<THandler<Self>, ConnectionDenied> {
         Ok(Handler::new(
-            ProtocolConfig::new(&self.config),
+            self.config.protocol_config(),
             self.config.idle_timeout(),
         ))
     }