Unify helpers IsRtpPacket and IsRtcpPacket

Bug: None
Change-Id: Ibe942de433435d256cd6827440136936d4b274d6
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/225022
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34419}

modules/rtp_rtcp/source/rtp_util.h

@@ -0,0 +1,25 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_RTP_RTCP_SOURCE_RTP_UTIL_H_
+#define MODULES_RTP_RTCP_SOURCE_RTP_UTIL_H_
+
+#include <cstdint>
+
+#include "api/array_view.h"
+
+namespace webrtc {
+
+bool IsRtcpPacket(rtc::ArrayView<const uint8_t> packet);
+bool IsRtpPacket(rtc::ArrayView<const uint8_t> packet);
+
+}  // namespace webrtc
+
+#endif  // MODULES_RTP_RTCP_SOURCE_RTP_UTIL_H_