refactor: Use Tokio's single-threaded runtime (#3844)

This change simplifies how we execute V8. Previously V8 Isolates jumped
around threads every time they were woken up. This was overly complex and
potentially hurting performance in a myriad ways. Now isolates run on
their own dedicated thread and never move.

- blocking_json spawns a thread and does not use a thread pool
- op_host_poll_worker and op_host_resume_worker are non-operational
- removes Worker::get_message and Worker::post_message
- ThreadSafeState::workers table contains WorkerChannel entries instead
  of actual Worker instances.
- MainWorker and CompilerWorker are no longer Futures.
- The multi-threaded version of deno_core_http_bench was removed.
- AyncOps no longer need to be Send + Sync

This PR is very large and several tests were disabled to speed
integration:
- installer_test_local_module_run
- installer_test_remote_module_run
- _015_duplicate_parallel_import
- _026_workers

cli/tokio_util.rs

@@ -1,15 +1,29 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+use futures::Future;
 
-#[cfg(test)]
-pub fn run<F>(future: F)
+// TODO(ry) rename to run_local ?
+pub fn run_basic<F, R>(future: F) -> R
 where
-  F: std::future::Future<Output = ()> + Send + 'static,
+  F: std::future::Future<Output = R> + 'static,
 {
   let mut rt = tokio::runtime::Builder::new()
-    .threaded_scheduler()
-    .enable_all()
-    .thread_name("deno")
+    .basic_scheduler()
+    .enable_io()
+    .enable_time()
     .build()
-    .expect("Unable to create Tokio runtime");
-  rt.block_on(future);
+    .unwrap();
+  rt.block_on(future)
+}
+
+pub fn spawn_thread<F, R>(f: F) -> impl Future<Output = R>
+where
+  F: 'static + Send + FnOnce() -> R,
+  R: 'static + Send,
+{
+  let (sender, receiver) = tokio::sync::oneshot::channel::<R>();
+  std::thread::spawn(move || {
+    let result = f();
+    sender.send(result)
+  });
+  async { receiver.await.unwrap() }
 }