[debug dump] Refactoring Modules and Unit Tests

[vivekrnv]

What I did

1. Moved the "populate_mock" method to dump/helper.py i.e. common to all the tests
2. Moved the "add_to_ret_template" to Executor class i.e. common across all the modules.

How I did it

How to verify it

Unit Tests's:

vkarri@96050efd4f16:/sonic/src/sonic-utilities$ pytest-3 tests/dump_tests/ 
=========================================================================== test session starts ============================================================================
platform linux -- Python 3.9.2, pytest-6.0.2, py-1.10.0, pluggy-0.13.0
rootdir: /sonic/src/sonic-utilities/tests, configfile: pytest.ini
plugins: pyfakefs-4.5.3, cov-2.10.1
collected 116 items                                                                                                                                                        

tests/dump_tests/dump_state_test.py .............                                                                                                                    [ 11%]
tests/dump_tests/match_engine_test.py ...............................                                                                                                [ 37%]
tests/dump_tests/module_tests/copp_test.py ..........                                                                                                                [ 46%]
tests/dump_tests/module_tests/evpn_test.py ......                                                                                                                    [ 51%]
tests/dump_tests/module_tests/port_test.py ......                                                                                                                    [ 56%]
tests/dump_tests/module_tests/portchannel_member_test.py ...                                                                                                         [ 59%]
tests/dump_tests/module_tests/portchannel_test.py ....                                                                                                               [ 62%]
tests/dump_tests/module_tests/route_test.py ..........                                                                                                               [ 71%]
tests/dump_tests/module_tests/vlan_test.py .....................                                                                                                     [ 89%]
tests/dump_tests/module_tests/vxlan_tunnel_map_test.py .....                                                                                                         [ 93%]
tests/dump_tests/module_tests/vxlan_tunnel_test.py .......                                                                                                           [100%]

=========================================================================== 116 passed in 1.21s ============================================================================

Previous command output (if the output of a command-line utility has changed)

New command output (if the output of a command-line utility has changed)

[vivekrnv]

@SuvarnaMeenakshi, Can you help review

[dgsudharsan]

@SuvarnaMeenakshi Your code review comments are handled here. Can you please review and signoff?

[SuvarnaMeenakshi]

lgtm