Add FBPortForwarding source code

Summary:
See FBPortForwarding/README.md for an explanation of what this is.
It's required for the upcoming support for physical iOS devices.

To simplify development of the JS app, We're going to bundle the pre-built PortForwardingMacApp
inside the repo, and inside the electron app (static/PortForwardingMacApp.app).
Adding this source so users can build it from source if they choose to.

Reviewed By: danielbuechele

Differential Revision: D13276022

fbshipit-source-id: 99b18e0412cf443bb4a67eb4846cc780e0014de1

iOS/FlipperKit/FKPortForwarding/FKPortForwardingCommon.h

@@ -0,0 +1,23 @@
+/**
+ * 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.
+ */
+#import <Foundation/Foundation.h>
+
+#define FBPFTrace(...) /*NSLog(__VA_ARGS__)*/
+#define FBPFLog(...) NSLog(__VA_ARGS__)
+
+enum {
+  FKPortForwardingFrameTypeOpenPipe = 201,
+  FKPortForwardingFrameTypeWriteToPipe = 202,
+  FKPortForwardingFrameTypeClosePipe = 203,
+};
+
+static dispatch_data_t NSDataToGCDData(NSData *data) {
+  __block NSData *retainedData = data;
+  return dispatch_data_create(data.bytes, data.length, nil, ^{
+    retainedData = nil;
+  });
+}