feat: P4 L2 simple service handler

src/service/service/service_handlers/__init__.py

...vice/service_handlers/p4_fabric_tna_l2_simple/__init__.py

...p4_fabric_tna_l2_simple/p4_fabric_tna_l2_simple_config.py

..._tna_l2_simple/p4_fabric_tna_l2_simple_service_handler.py

src/tests/p4-fabric-tna/README.md

...s/p4-fabric-tna/descriptors/service-create-l2-simple.json

src/tests/p4-fabric-tna/run_test_03a_service_provision_l2.sh

...ests/p4-fabric-tna/run_test_03b_service_deprovision_l2.sh

...a/tests-service/test_functional_service_deprovision_l2.py

...tna/tests-service/test_functional_service_provision_l2.py

src/tests/tools/test_tools_p4.py