[nexus] add SRP-TC-11 for recovery after reboot (#12772)

This commit adds the Nexus test case 1_3_SRP_TC_11 which verifies that
SRP registration and mDNS discovery are correctly recovered after
various device reboots, as per the Thread 1.3 test specification.

The implementation includes:
- tests/nexus/test_1_3_SRP_TC_11.cpp: Executes the test sequence by
  simulating reboots of a Thread End Device (ED_1), a Border Router
  (BR_1), and an Infrastructure node (Eth_1). It ensures consistent
  network datasets across reboots and uses direct method calls for
  configuration.
- tests/nexus/verify_1_3_SRP_TC_11.py: Performs automated verification
  of the captured traffic (PCAP). It uses specific MAC address filters
  to reliably identify mDNS queries and responses across multiple
  reboot scenarios where protocol exchanges may otherwise appear
  identical.
- Integrated the new test into tests/nexus/CMakeLists.txt and
  tests/nexus/run_nexus_tests.sh.

The test ensures that SRP clients automatically re-register after
device or server reboots and that the BR correctly continues to
respond to mDNS queries on the infrastructure interface.

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

@@ -691,6 +691,8 @@ _LAYER_FIELDS = {
     'dns.resp.type': _list(_auto),
     'dns.aaaa': _list(_ipv6_addr),
     'dns.txt': _list(_bytes),
+    'dns.srv.priority': _list(_auto),
+    'dns.srv.weight': _list(_auto),
     'dns.srv.port': _list(_auto),
     'dns.srv.target': _list(_str),
     'dns.ptr.domain_name': _list(_str),
@@ -707,6 +709,8 @@ _LAYER_FIELDS = {
     'mdns.resp.type': _list(_auto),
     'mdns.aaaa': _list(_ipv6_addr),
     'mdns.txt': _list(_bytes),
+    'mdns.srv.priority': _list(_auto),
+    'mdns.srv.weight': _list(_auto),
     'mdns.srv.port': _list(_auto),
     'mdns.srv.target': _list(_str),
     'mdns.ptr.domain_name': _list(_str),