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/eth1/Cargo.toml

@@ -6,7 +6,6 @@ edition = "2018"
 
 [dev-dependencies]
 eth1_test_rig = { path = "../../testing/eth1_test_rig" }
-environment = { path = "../../lighthouse/environment" }
 toml = "0.5.6"
 web3 = "0.11.0"
 sloggers = "1.0.0"
@@ -25,8 +24,9 @@ tree_hash = "0.1.0"
 eth2_hashing = "0.1.0"
 parking_lot = "0.10.2"
 slog = "2.5.2"
-tokio = { version = "0.2.20", features = ["full"] }
+tokio = { version = "0.2.21", features = ["full"] }
 state_processing = { path = "../../consensus/state_processing" }
 libflate = "1.0.0"
 lighthouse_metrics = { path = "../../common/lighthouse_metrics"}
 lazy_static = "1.4.0"
+environment = { path = "../../lighthouse/environment" }