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

testing/libfuzzer/fuzzers/dns_record_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/dns/dns_response.h"
-
-// Entry point for LibFuzzer.
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  net::DnsRecordParser parser(data, size, 0);
-  if (!parser.IsValid()) {
-    return 0;
-  }
-  net::DnsResourceRecord record;
-  while (parser.ReadRecord(&record)) {
-  }
-  return 0;
-}