fix(ci): ensure all examples compile with the specified feature-set

Due to cargo's feature unification, a full build of our workspace doesn't actually check whether the examples compile as standalone projects.

We add a new CI check that iterates through all crates in the `examples/` directory and runs a plain `cargo check` on them. Any failure is bubbled up via `set -e`, thus failing CI in case one of the `cargo check` commands fails.

To fix the current failures, we construct a simple TCP transport everywhere where we were previously using `development_transport`. That is because `development_transport` requires `mplex` which is now deprecated.

Related #3657.
Related #3809.

Pull-Request: #3811.

examples/ping-example/src/main.rs

@@ -41,10 +41,11 @@
 //! and begin pinging each other.
 
 use futures::prelude::*;
+use libp2p::core::upgrade::Version;
 use libp2p::{
-    identity, ping,
+    identity, noise, ping,
     swarm::{keep_alive, NetworkBehaviour, SwarmBuilder, SwarmEvent},
-    Multiaddr, PeerId,
+    tcp, yamux, Multiaddr, PeerId, Transport,
 };
 use std::error::Error;
 
@@ -54,7 +55,11 @@ async fn main() -> Result<(), Box<dyn Error>> {
     let local_peer_id = PeerId::from(local_key.public());
     println!("Local peer id: {local_peer_id:?}");
 
-    let transport = libp2p::development_transport(local_key).await?;
+    let transport = tcp::async_io::Transport::default()
+        .upgrade(Version::V1Lazy)
+        .authenticate(noise::NoiseAuthenticated::xx(&local_key)?)
+        .multiplex(yamux::YamuxConfig::default())
+        .boxed();
 
     let mut swarm =
         SwarmBuilder::with_async_std_executor(transport, Behaviour::default(), local_peer_id)