[nexus] migrate test_pbbr_aloc.py to nexus (#12989)

This commit migrates the 'test_pbbr_aloc.py' script from the
thread-cert framework to the Nexus simulation framework.

The new 'test_pbbr_aloc.cpp' replicates the original test:
- Forms a network with PBBR, Leader, and Router nodes.
- Enables Backbone Router (BBR) on the PBBR node and waits for it
  to become the Primary BBR.
- Verifies connectivity to the Leader ALOC (0xfc00) and the PBBR
  ALOC (0xfc38) from the Router node using ICMPv6 Echo Requests.
- Confirms that the stack correctly uses Network Data for ALOC
  resolution.

Nexus tests provide faster and more scalable network simulations
within a single process, improving CI efficiency and reliability.

Original Python script 'tests/scripts/thread-cert/test_pbbr_aloc.py'
is removed as its functionality is now fully covered by Nexus.

tests/scripts/thread-cert/test_pbbr_aloc.py

@@ -1,117 +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 re
-import unittest
-
-import config
-import thread_cert
-from config import MESH_LOCAL_PREFIX_REGEX_PATTERN, ROUTING_LOCATOR_REGEX_PATTERN
-from pktverify.packet_verifier import PacketVerifier
-
-# Test description:
-# The purpose of this test is to verify ALOC connectivity.
-#
-# Topology:
-#
-#
-#  PBBR ----- LEADER ---- ROUTER
-#
-#
-
-LEADER = 1
-PBBR = 2
-ROUTER = 3
-
-
-class TestPing(thread_cert.TestCase):
-    USE_MESSAGE_FACTORY = False
-    SUPPORT_NCP = False
-    SUPPORT_THREAD_1_1 = False
-
-    TOPOLOGY = {
-        LEADER: {
-            'name': 'Router_1',
-            'allowlist': [PBBR, ROUTER],
-        },
-        PBBR: {
-            'name': 'Router_2',
-            'allowlist': [LEADER],
-            'is_bbr': True,
-        },
-        ROUTER: {
-            'name': 'Router_3',
-            'allowlist': [LEADER],
-        },
-    }
-
-    def test(self):
-        leader = self.nodes[LEADER]
-        pbbr = self.nodes[PBBR]
-        router = self.nodes[ROUTER]
-
-        leader.start()
-        self.simulator.go(config.LEADER_STARTUP_DELAY)
-        self.assertEqual('leader', leader.get_state())
-
-        pbbr.enable_backbone_router()
-        pbbr.start()
-        self.simulator.go(config.ROUTER_STARTUP_DELAY)
-        self.assertEqual('router', pbbr.get_state())
-        self.assertTrue(pbbr.is_primary_backbone_router)
-
-        router.start()
-        self.simulator.go(config.ROUTER_STARTUP_DELAY)
-        self.assertEqual('router', router.get_state())
-
-        for node in (leader, pbbr):
-            for addr in self.get_alocs(node):
-                self.assertTrue(router.ping(addr))
-
-    def verify(self, pv: PacketVerifier):
-        pkts = pv.pkts
-        # Must sure no ADDR_QUERY.qry is ever sent
-        pkts.filter_coap_request('/a/aq').must_not_next()
-
-    def get_alocs(self, node):
-        mleid = node.get_mleid()
-        for ip in node.get_addrs():
-            if not re.match(MESH_LOCAL_PREFIX_REGEX_PATTERN, ip):
-                continue
-
-            if ip == mleid:
-                continue
-
-            self.assertIsNotNone(re.match(ROUTING_LOCATOR_REGEX_PATTERN, ip), ip)
-            locator = int(ip.split(':')[-1], 16)
-            if locator >= 0xfc00:
-                yield ip
-
-
-if __name__ == '__main__':
-    unittest.main()