Add a name to the Tokio task (#7544)

The `console-subscriber` feature was added in https://github.com/sigp/lighthouse/pull/7529. However, the names of the running tasks are blank:

<img width="780" alt="image" src="https://github.com/user-attachments/assets/73332a03-20c6-43ba-b810-3d0a898bb236" />


  Set the task name using `tokio::task::Builder`, which is availble when the `tokio_unstable` is enabled.

<img width="924" alt="image" src="https://github.com/user-attachments/assets/26bdac1a-348b-4f83-84b0-adfd2ba3a8cb" />

common/task_executor/Cargo.toml

@@ -10,3 +10,6 @@ futures = { workspace = true }
 metrics = { workspace = true }
 tokio = { workspace = true, features = ["rt-multi-thread", "macros"] }
 tracing = { workspace = true }
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ["cfg(tokio_unstable)"] }

common/task_executor/src/lib.rs

@@ -144,7 +144,7 @@ impl TaskExecutor {
     ) {
         let mut shutdown_sender = self.shutdown_sender();
         if let Some(handle) = self.handle() {
-            handle.spawn(async move {
+            let fut = async move {
                 let timer = metrics::start_timer_vec(&metrics::TASKS_HISTOGRAM, &[name]);
                 if let Err(join_error) = task_handle.await {
                     if let Ok(_panic) = join_error.try_into_panic() {
@@ -153,7 +153,14 @@ impl TaskExecutor {
                     }
                 }
                 drop(timer);
-            });
+            };
+            #[cfg(tokio_unstable)]
+            tokio::task::Builder::new()
+                .name(&format!("{name}-monitor"))
+                .spawn_on(fut, &handle)
+                .expect("Failed to spawn monitor task");
+            #[cfg(not(tokio_unstable))]
+            handle.spawn(fut);
         } else {
             debug!("Couldn't spawn monitor task. Runtime shutting down")
         }
@@ -199,6 +206,12 @@ impl TaskExecutor {
 
             int_gauge.inc();
             if let Some(handle) = self.handle() {
+                #[cfg(tokio_unstable)]
+                tokio::task::Builder::new()
+                    .name(name)
+                    .spawn_on(future, &handle)
+                    .expect("Failed to spawn task");
+                #[cfg(not(tokio_unstable))]
                 handle.spawn(future);
             } else {
                 debug!("Couldn't spawn task. Runtime shutting down");
@@ -234,7 +247,7 @@ impl TaskExecutor {
             let int_gauge_1 = int_gauge.clone();
             int_gauge.inc();
             if let Some(handle) = self.handle() {
-                Some(handle.spawn(async move {
+                let fut = async move {
                     futures::pin_mut!(exit);
                     let result = match future::select(Box::pin(task), exit).await {
                         future::Either::Left((value, _)) => Some(value),
@@ -245,7 +258,16 @@ impl TaskExecutor {
                     };
                     int_gauge_1.dec();
                     result
-                }))
+                };
+                #[cfg(tokio_unstable)]
+                return Some(
+                    tokio::task::Builder::new()
+                        .name(name)
+                        .spawn_on(fut, &handle)
+                        .expect("Failed to spawn task"),
+                );
+                #[cfg(not(tokio_unstable))]
+                Some(handle.spawn(fut))
             } else {
                 debug!("Couldn't spawn task. Runtime shutting down");
                 None