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 58d4bb690f.

* 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/eth2-libp2p/tests/noise.rs

@@ -136,7 +136,10 @@ async fn test_secio_noise_fallback() {
 
     let port = common::unused_port("tcp").unwrap();
     let noisy_config = common::build_config(port, vec![], None);
-    let mut noisy_node = Service::new(&noisy_config, EnrForkId::default(), &log)
+    let (_signal, exit) = exit_future::signal();
+    let executor =
+        environment::TaskExecutor::new(tokio::runtime::Handle::current(), exit, log.clone());
+    let mut noisy_node = Service::new(executor, &noisy_config, EnrForkId::default(), &log)
         .expect("should build a libp2p instance")
         .1;