Improve tokio task execution (#1181)

* Add logging on shutdown

* Replace tokio::spawn with handle.spawn

* Upgrade tokio

* Add a task executor

* Beacon chain tasks use task executor

* Validator client tasks use task executor

* Rename runtime_handle to executor

* Add duration histograms; minor fixes

* Cleanup

* Fix logs

* Fix tests

* Remove random file

* Get enr dependency instead of libp2p

* Address some review comments

* Libp2p takes a TaskExecutor

* Ugly fix libp2p tests

* Move TaskExecutor to own file

* Upgrade Dockerfile rust version

* Minor fixes

* Revert "Ugly fix libp2p tests"

This reverts commit 58d4bb690f52de28d893943b7504d2d0c6621429.

* Pretty fix libp2p tests

* Add spawn_without_exit; change Counter to Gauge

* Tidy

* Move log from RuntimeContext to TaskExecutor

* Fix errors

* Replace histogram with int_gauge for async tasks

* Fix todo

* Fix memory leak in test by exiting all spawned tasks at the end

beacon_node/network/src/service/tests.rs

@@ -32,7 +32,9 @@ mod tests {
         let enrs = vec![enr1, enr2];
 
         let runtime = Runtime::new().unwrap();
-        let handle = runtime.handle().clone();
+
+        let (signal, exit) = exit_future::signal();
+        let executor = environment::TaskExecutor::new(runtime.handle().clone(), exit, log.clone());
 
         let mut config = NetworkConfig::default();
         config.libp2p_port = 21212;
@@ -42,8 +44,8 @@ mod tests {
             // Create a new network service which implicitly gets dropped at the
             // end of the block.
 
-            let _ =
-                NetworkService::start(beacon_chain.clone(), &config, &handle, log.clone()).unwrap();
+            let _ = NetworkService::start(beacon_chain.clone(), &config, executor).unwrap();
+            drop(signal);
         });
         runtime.shutdown_timeout(tokio::time::Duration::from_millis(300));