[scripts] add packet verification framework (#4428)

This commit introduces the packet verification (PV) framework for
certification tests.

- Add packet verification framework code

- Implement packet verification for cert 5.1.7 as a minimal
  example. There will be more 1.1/1.2 tests with PV submitted in the
  future.

- Download pre-built thread-wireshark binaries from
  openthread/wireshark/releases for packet dissecting (used by
  pyshark)

- Added a Github Action job for Packet Verification

tests/scripts/thread-cert/pktverify/errors.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python3
+#
+#  Copyright (c) 2019, The OpenThread Authors.
+#  All rights reserved.
+#
+#  Redistribution and use in source and binary forms, with or without
+#  modification, are permitted provided that the following conditions are met:
+#  1. Redistributions of source code must retain the above copyright
+#     notice, this list of conditions and the following disclaimer.
+#  2. Redistributions in binary form must reproduce the above copyright
+#     notice, this list of conditions and the following disclaimer in the
+#     documentation and/or other materials provided with the distribution.
+#  3. Neither the name of the copyright holder nor the
+#     names of its contributors may be used to endorse or promote products
+#     derived from this software without specific prior written permission.
+#
+#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+#  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+#  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+#  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+#  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+#  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+#  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+#  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+#  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+#  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+#  POSSIBILITY OF SUCH DAMAGE.
+#
+
+
+class Error(Exception):
+    """
+    Base error class for all Packet Verification errors.
+    """
+    pass
+
+
+class PacketNotFound(Error):
+    """
+    Represents an error that the packet was not found.
+    """
+
+    def __init__(self, start_index, stop_index):
+        self._start_index = start_index
+        self._stop_index = stop_index
+
+
+class UnexpectedPacketFound(Error):
+    """
+    Represents an error that the packet was found unexpectedly.
+    """
+
+    def __init__(self, idx, pkt):
+        self._idx = idx
+        self._pkt = pkt
+
+
+class VerifyFailed(Error):
+    """
+    Represents an error that the packet failed to pass verification criteria.
+    """
+
+    def __init__(self, pkt):
+        self._pkt = pkt