[P4_Symbolic] Add support for VLAN header. Fix SAI VLAN header existence check.

[VSuryaprasad-HCL]

Keyword Check:
~/sonic-buildimage/src/sonic-p4rt/sonic-pins$ ~/tools/keyword_checks.sh .
Keyword check Passed.

Build Result:
/sonic/src/sonic-p4rt/sonic-pins$ bazel build $BAZEL_BUILD_OPTS ...
INFO: Analyzed 645 targets (0 packages loaded, 0 targets configured).
INFO: Found 645 targets...
standard_metadata.ingress_port = #b000000000
standard_metadata.instance_type = #x00000000
standard_metadata.mcast_grp = #x0000
standard_metadata.packet_length = #x00000000
standard_metadata.parser_error = #x00000000
standard_metadata.priority = #b000

egress_headers:
$got_cloned$ = false
h1.$extracted$ = true
h1.$valid$ = true
h1.f1 = #x00
h1.f2 = #x00
h1.f3 = #x00
h1.f4 = #x00
h1.f5 = #x00
h1.f6 = #x00
h1.f7 = #x00
h1.f8 = #x00
h1.fr = #xff
h1.fw = #x01
scalars.$extracted$ = false
scalars.$valid$ = false
standard_metadata.$extracted$ = false
standard_metadata.$valid$ = false
standard_metadata._padding = #b000
standard_metadata.checksum_error = #b0
standard_metadata.deq_qdepth = #b0000000000000000000
standard_metadata.deq_timedelta = #x00000000
standard_metadata.egress_global_timestamp = #x000000000000
standard_metadata.egress_port = #b000000000
standard_metadata.egress_rid = #x0000
standard_metadata.egress_spec = #b000000000
standard_metadata.enq_qdepth = #b0000000000000000000
standard_metadata.enq_timestamp = #x00000000
standard_metadata.ingress_global_timestamp = #x000000000000
standard_metadata.ingress_port = #b000000000
standard_metadata.instance_type = #x00000000
standard_metadata.mcast_grp = #x0000
standard_metadata.packet_length = #x00000000
standard_metadata.parser_error = #x00000000
standard_metadata.priority = #b000

---

INFO: Elapsed time: 7.795s, Critical Path: 6.96s
INFO: 15 processes: 2 internal, 13 linux-sandbox.
INFO: Build completed successfully, 15 total actions

Test Result:
/sonic/src/sonic-p4rt/sonic-pins$ bazel test $BAZEL_BUILD_OPTS --cache_test_results=no ...
INFO: Analyzed 645 targets (0 packages loaded, 0 targets configured).
INFO: Found 430 targets and 215 test targets...
INFO: Elapsed time: 183.319s, Critical Path: 120.43s
INFO: 269 processes: 325 linux-sandbox, 18 local.
INFO: Build completed successfully, 269 total actions
//dvaas:port_id_map_test PASSED in 0.8s
//dvaas:test_run_validation_golden_test PASSED in 0.1s
//dvaas:test_run_validation_test PASSED in 0.7s
//dvaas:test_run_validation_test_runner PASSED in 0.0s
//dvaas:test_vector_stats_diff_test PASSED in 0.1s
//dvaas:test_vector_stats_test PASSED in 0.0s
//dvaas:test_vector_test PASSED in 0.6s
//dvaas:user_provided_packet_test_vector_diff_test PASSED in 0.1s
//dvaas:user_provided_packet_test_vector_test PASSED in 0.1s
//gutil:collections_test PASSED in 0.5s
//gutil:io_test PASSED in 0.5s
//gutil:proto_matchers_test PASSED in 0.6s
//gutil:proto_ordering_test PASSED in 0.5s
//p4rt_app/utils:table_utility_test PASSED in 0.9s
//sai_p4/instantiations/google:clos_stage_test PASSED in 0.5s
//sai_p4/instantiations/google:fabric_border_router_p4info_up_to_date_test PASSED in 0.0s
//sai_p4/instantiations/google:middleblock_p4info_up_to_date_test PASSED in 0.0s
//sai_p4/instantiations/google:sai_nonstandard_platforms_build_test PASSED in 0.0s
//sai_p4/instantiations/google:sai_nonstandard_platforms_cc_test PASSED in 0.6s
//sai_p4/instantiations/google:sai_p4info_fetcher_test PASSED in 0.7s
//sai_p4/instantiations/google:sai_p4info_test PASSED in 1.2s
//sai_p4/instantiations/google:sai_pd_proto_test PASSED in 0.0s
//sai_p4/instantiations/google:sai_pd_util_test PASSED in 0.6s
//sai_p4/instantiations/google:tor_p4info_up_to_date_test PASSED in 0.0s
//sai_p4/instantiations/google:union_p4info_up_to_date_test PASSED in 0.1s
//sai_p4/instantiations/google:wbb_p4info_up_to_date_test PASSED in 0.0s
//sai_p4/instantiations/google/test_tools:table_entry_generator_helper_test PASSED in 1.5s
//sai_p4/instantiations/google/test_tools:test_entries_test PASSED in 1.1s
//sai_p4/instantiations/google/tests:p4_fuzzer_integration_test PASSED in 3.4s
//sai_p4/tools:p4info_tools_test PASSED in 0.7s
//sai_p4/tools:packetio_tools_test PASSED in 1.0s
//tests:thinkit_gnmi_interface_util_tests PASSED in 1.1s
//tests/lib:p4info_helper_test PASSED in 0.9s
//tests/lib:p4rt_fixed_table_programming_helper_test PASSED in 0.7s
//tests/lib:packet_generator_test PASSED in 27.2s
//tests/lib:switch_test_setup_helpers_golden_test PASSED in 0.1s
//tests/lib:switch_test_setup_helpers_golden_test_runner PASSED in 0.2s
//tests/qos:gnmi_parsers_test PASSED in 0.1s
//tests/qos:gnmi_parsers_test_runner PASSED in 0.0s
//tests/sflow:sflow_util_test PASSED in 0.9s
//thinkit:bazel_test_environment_test PASSED in 0.6s
//thinkit:generic_testbed_test PASSED in 1.0s
//thinkit:mock_control_device_test PASSED in 0.5s
//thinkit:mock_generic_testbed_test PASSED in 0.7s
//thinkit:mock_mirror_testbed_test PASSED in 0.6s
//thinkit:mock_ssh_client_test PASSED in 0.0s
//thinkit:mock_switch_test PASSED in 0.7s
//thinkit:mock_test_environment_test PASSED in 0.1s
//thinkit:switch_test PASSED in 0.8s
//sai_p4/instantiations/google/tests:p4_constraints_integration_test PASSED in 0.9s
Stats over 5 runs: max = 0.9s, min = 0.7s, avg = 0.8s, dev = 0.1s
//sai_p4/instantiations/google/test_tools:table_entry_generator_test PASSED in 44.8s
Stats over 50 runs: max = 44.8s, min = 0.8s, avg = 4.4s, dev = 10.2s

Executed 215 out of 215 tests: 215 tests pass.
INFO: Build completed successfully, 269 total actions

[mssonicbld]

/azp run

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[VSuryaprasad-HCL]

Co-authored-by:kheradmandG kheradmand@google.com

[divyagayathri-hcl]

@kishanps, Could you please review.
Thanks.

[mssonicbld]

/azp run

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