[nexus] migrate dataset_updater test to nexus (#12920)

This commit migrates the dataset_updater functional test from the
Python-based thread-cert framework to the Nexus simulation framework.

Nexus provides faster and more scalable network simulations within a
single process using virtual time.

The new test_dataset_updater.cpp covers:
- Network formation and child joining (MED and SED).
- Channel updates initiated by Leader and Router using DatasetUpdater.
- Dataset update overrides between nodes.

The legacy tests/scripts/thread-cert/test_dataset_updater.py is removed
as it is now redundant.

tests/scripts/thread-cert/test_dataset_updater.py

@@ -1,118 +0,0 @@
-#!/usr/bin/env python3
-#
-#  Copyright (c) 2021, 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.
-#
-
-import unittest
-
-import config
-import thread_cert
-
-LEADER = 1
-ROUTER = 2
-MED = 3
-SED = 4
-
-
-class TestDatasetUpdater(thread_cert.TestCase):
-    SUPPORT_NCP = False
-    USE_MESSAGE_FACTORY = False
-
-    TOPOLOGY = {
-        LEADER: {
-            'mode': 'rdn',
-            'channel': 11,
-        },
-        ROUTER: {
-            'mode': 'rdn',
-            'channel': 11,
-        },
-        MED: {
-            'mode': 'rn',
-            'channel': 11,
-            'allowlist': [ROUTER],
-        },
-        SED: {
-            'mode': '-',
-            'channel': 11,
-            'timeout': config.DEFAULT_CHILD_TIMEOUT,
-            'allowlist': [ROUTER],
-        },
-    }
-
-    def test(self):
-        self.nodes[LEADER].start()
-        self.simulator.go(config.LEADER_STARTUP_DELAY)
-        self.assertEqual(self.nodes[LEADER].get_state(), 'leader')
-
-        self.nodes[ROUTER].start()
-        self.simulator.go(config.ROUTER_STARTUP_DELAY)
-        self.assertEqual(self.nodes[ROUTER].get_state(), 'router')
-
-        self.nodes[MED].start()
-        self.simulator.go(5)
-        self.assertEqual(self.nodes[MED].get_state(), 'child')
-
-        self.nodes[SED].start()
-        self.simulator.go(5)
-        self.assertEqual(self.nodes[SED].get_state(), 'child')
-
-        self.verify_state(11)
-
-        # update initiated by LEADER
-        self.nodes[LEADER].start_dataset_updater(channel=12)
-        self.simulator.go(120)
-        self.verify_state(12)
-
-        # update initiated by ROUTER
-        self.nodes[ROUTER].start_dataset_updater(channel=13)
-        self.simulator.go(120)
-        self.verify_state(13)
-
-        # update initiated by LEADER overridden by ROUTER
-        self.nodes[LEADER].start_dataset_updater(channel=14)
-        self.simulator.go(20)
-        self.nodes[ROUTER].start_dataset_updater(channel=15)
-        self.simulator.go(120)
-        self.verify_state(15)
-
-        # update initiated by ROUTER overridden by LEADER
-        self.nodes[ROUTER].start_dataset_updater(channel=16)
-        self.simulator.go(10)
-        self.nodes[LEADER].start_dataset_updater(channel=17)
-        self.simulator.go(120)
-        self.verify_state(17)
-
-    def verify_state(self, channel):
-        self.assertEqual(self.nodes[LEADER].get_channel(), channel)
-        self.assertEqual(self.nodes[ROUTER].get_channel(), channel)
-        self.assertEqual(self.nodes[MED].get_channel(), channel)
-        self.assertEqual(self.nodes[SED].get_channel(), channel)
-
-
-if __name__ == '__main__':
-    unittest.main()