[Dvaas]: Adding Traffic generator code to dvaas.

[VSuryaprasad-HCL]

Key_word Check:

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

Build result:

/sonic/src/sonic-p4rt/sonic-pins$ bazel build $BAZEL_BUILD_OPTS ...
INFO: Analyzed 621 targets (0 packages loaded, 0 targets configured).
INFO: Found 621 targets...
INFO: Elapsed time: 0.457s, Critical Path: 0.00s
INFO: 1 process: 1 internal.
INFO: Build completed successfully, 1 total action

Test result:

/sonic/src/sonic-p4rt/sonic-pins$ bazel test $BAZEL_BUILD_OPTS --cache_test_results=no ...
INFO: Analyzed 621 targets (0 packages loaded, 362 targets configured).
INFO: Found 415 targets and 206 test targets...
INFO: Elapsed time: 163.586s, Critical Path: 117.58s
INFO: 260 processes: 313 linux-sandbox, 18 local.
INFO: Build completed successfully, 260 total actions
//dvaas:port_id_map_test                                                 PASSED in 1.0s
//dvaas:test_run_validation_golden_test                                  PASSED in 0.2s
//dvaas:test_run_validation_test                                         PASSED in 1.0s
//dvaas:test_run_validation_test_runner                                  PASSED in 0.2s
//thinkit:mock_mirror_testbed_test                                       PASSED in 0.9s
//thinkit:mock_ssh_client_test                                           PASSED in 0.1s
//thinkit:mock_switch_test                                               PASSED in 1.7s
//thinkit:mock_test_environment_test                                     PASSED in 0.3s
//thinkit:switch_test                                                    PASSED in 0.8s
//sai_p4/instantiations/google/tests:p4_constraints_integration_test     PASSED in 1.3s
  Stats over 5 runs: max = 1.3s, min = 1.0s, avg = 1.1s, dev = 0.1s
//sai_p4/instantiations/google/test_tools:table_entry_generator_test     PASSED in 43.6s
  Stats over 50 runs: max = 43.6s, min = 1.2s, avg = 3.7s, dev = 8.3s

Executed 206 out of 206 tests: 206 tests pass.
INFO: Build completed successfully, 260 total actions

[bibhuprasad-hcl]

@kishanps, Could you please review.
Thanks.