Partially remove dependency on folly async

Summary:
This change isolates the usage of folly async from Flipper. Is now self-contained in Flipper Folly schedulers.

Users of Flipper can decide not to use the types defined in that header and implement their own.

NOTE: changes are minimal, we are just replacing direct calls to folly event base with a scheduler which simply relays this on to folly.

Reviewed By: fabiomassimo

Differential Revision: D36052198

fbshipit-source-id: 170d64a324a1f1f100224e2622a59cbac3c8b642

xplat/Flipper/FlipperConnectionManagerImpl.h

@@ -7,11 +7,10 @@
 
 #pragma once
 
-#include <folly/Executor.h>
-#include <folly/io/async/EventBase.h>
 #include <mutex>
 #include "FlipperConnectionManager.h"
 #include "FlipperInitConfig.h"
+#include "FlipperScheduler.h"
 #include "FlipperSocket.h"
 #include "FlipperState.h"
 
@@ -64,8 +63,8 @@ class FlipperConnectionManagerImpl : public FlipperConnectionManager {
   int altInsecurePort;
   int altSecurePort;
 
-  folly::EventBase* flipperEventBase_;
-  folly::EventBase* connectionEventBase_;
+  Scheduler* flipperScheduler_;
+  Scheduler* connectionScheduler_;
 
   std::unique_ptr<FlipperSocket> client_;