Upgrade tokio to 1.22.0 and replace async-std with tokio (#12646)

* Replace deprecated libp2p feature specs with correct ones

* Bump tokio to 1.21.2

* Replace async-std libp2p primitives with tokio ones

* minor: rustfmt

* Fix TestNet to run initialization in the tokio context

* Convert telemetry test from async-std to tokio

* Convert notifications tests from async-std to tokio

* Convert chain sync tests from async-std to tokio

* Ditch async-std completely

* Make executor mandatory

* Bump tokio to 1.22.0

* minor: rustfmt

* Explicitly use tokio runtime in tests

* Move more tests to explicit tokio runtime

* Explicitly set multithreaded runtime in tokio test

* minor: rustfmt

* minor: fix comment

* Replace async-std with tokio in MMR tests

substrate/client/network/sync/src/tests.rs

@@ -35,7 +35,7 @@ use substrate_test_runtime_client::{TestClientBuilder, TestClientBuilderExt as _
 
 // verify that the fork target map is empty, then submit a new sync fork request,
 // poll `ChainSync` and verify that a new sync fork request has been registered
-#[async_std::test]
+#[tokio::test]
 async fn delegate_to_chainsync() {
 	let (_chain_sync_network_provider, chain_sync_network_handle) = NetworkServiceProvider::new();
 	let (mut chain_sync, chain_sync_service, _) = ChainSync::new(