Move devices to server folder

Summary:
This is the first of many diffs that extracts the connection, device, client detection out of the flipper core, to create a reusable flipper-server library that can be used in e.g. flipper-dump.

To keep diffs a little smaller, the current connection logic is first moved to the `server/` directory, and decoupled manually from the rest of the core, before moving it over to a separate package.

This first diffs moves the `comms/`, `devices/` and certificate utilities to the `server` directory.

Further untangling will follow in next diffs

Reviewed By: timur-valiev

Differential Revision: D30246551

fbshipit-source-id: c84259bfb1239119b3267a51b015e30c3c080866

desktop/flipper-plugin/src/utils/timeout.tsx

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import {sleep} from './sleep';
+
+export function timeout<T>(
+  ms: number,
+  promise: Promise<T>,
+  timeoutMessage?: string,
+): Promise<T> {
+  // Create a promise that rejects in <ms> milliseconds
+  const timeout = sleep(ms).then(() => {
+    throw new Error(timeoutMessage || `Timed out in ${ms} ms.`);
+  });
+
+  // Returns a race between our timeout and the passed in promise
+  return Promise.race([promise, timeout]);
+}