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: D36626483

fbshipit-source-id: add0241caf4af0aa5c3b5c2e7efc2e725f5400ab

xplat/Flipper/FlipperSocketProvider.cpp

@@ -21,19 +21,19 @@ std::unique_ptr<FlipperSocketProvider> FlipperSocketProvider::shelvedProvider_ =
 std::unique_ptr<FlipperSocket> FlipperSocketProvider::socketCreate(
     FlipperConnectionEndpoint endpoint,
     std::unique_ptr<FlipperSocketBasePayload> payload,
-    folly::EventBase* eventBase) {
-  return provider_->create(std::move(endpoint), std::move(payload), eventBase);
+    Scheduler* scheduler) {
+  return provider_->create(std::move(endpoint), std::move(payload), scheduler);
 }
 
 std::unique_ptr<FlipperSocket> FlipperSocketProvider::socketCreate(
     FlipperConnectionEndpoint endpoint,
     std::unique_ptr<FlipperSocketBasePayload> payload,
-    folly::EventBase* eventBase,
+    Scheduler* scheduler,
     ConnectionContextStore* connectionContextStore) {
   return provider_->create(
       std::move(endpoint),
       std::move(payload),
-      eventBase,
+      scheduler,
       connectionContextStore);
 }