Move network fuzzers from //testing/libfuzzer/fuzzers to //net

testing/libfuzzer/fuzzers/ftp_ctrl_response_fuzzer.cc

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include <stddef.h>
-#include <stdint.h>
-
-#include "net/ftp/ftp_ctrl_response_buffer.h"
-#include "net/log/net_log.h"
-
-// Entry point for LibFuzzer.
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  const net::BoundNetLog log;
-  net::FtpCtrlResponseBuffer buffer(log);
-  if (!buffer.ConsumeData(reinterpret_cast<const char*>(data), size)) {
-    return 0;
-  }
-  while (buffer.ResponseAvailable()) {
-    (void)buffer.PopResponse();
-  }
-  return 0;
-}