Update on "Config manager supports command line overrides"

Summary:
PR implements following enhancements to config manager.
1. Command line args and toml file args are now unified.
2. Defaults can be loaded from either.
3. Defaults can be overridden through command line. Overrides will
be applied irrespective of where the defaults were loaded from.

Test Plan:
============================= test session starts ==============================
platform linux -- Python 3.10.13, pytest-8.0.1, pluggy-1.4.0 -- /home/gnadathur/local/a/pytorch-env/bin/python
cachedir: .pytest_cache
rootdir: /data/users/gnadathur/a/torchtrain
configfile: pyproject.toml
plugins: cov-4.1.0
collecting ... collected 5 items

test/test_job_config.py::TestJobConfig::test_command_line_args PASSED    [ 20%]
test/test_job_config.py::TestJobConfig::test_command_line_args_with_override PASSED [ 40%]
test/test_job_config.py::TestJobConfig::test_job_config_file PASSED      [ 60%]
test/test_job_config.py::TestJobConfig::test_job_config_file_with_override PASSED [ 80%]
test/test_job_config.py::TestJobConfig::test_job_file_does_not_exist PASSED [100%]

---------- coverage: platform linux, python 3.10.13-final-0 ----------
Coverage XML written to file coverage.xml

============================= slowest 20 durations =============================
0.01s call     test/test_job_config.py::TestJobConfig::test_job_config_file_with_override
0.00s call     test/test_job_config.py::TestJobConfig::test_job_config_file
0.00s call     test/test_job_config.py::TestJobConfig::test_command_line_args
0.00s call     test/test_job_config.py::TestJobConfig::test_command_line_args_with_override
0.00s call     test/test_job_config.py::TestJobConfig::test_job_file_does_not_exist
0.00s setup    test/test_job_config.py::TestJobConfig::test_command_line_args
0.00s teardown test/test_job_config.py::TestJobConfig::test_command_line_args
0.00s setup    test/test_job_config.py::TestJobConfig::test_job_file_does_not_exist
0.00s setup    test/test_job_config.py::TestJobConfig::test_command_line_args_with_override
0.00s teardown test/test_job_config.py::TestJobConfig::test_command_line_args_with_override
0.00s setup    test/test_job_config.py::TestJobConfig::test_job_config_file_with_override
0.00s setup    test/test_job_config.py::TestJobConfig::test_job_config_file
0.00s teardown test/test_job_config.py::TestJobConfig::test_job_file_does_not_exist
0.00s teardown test/test_job_config.py::TestJobConfig::test_job_config_file
0.00s teardown test/test_job_config.py::TestJobConfig::test_job_config_file_with_override
============================== 5 passed in 0.10s ===============================

Successful 10 iterations llama.sh run

Reviewers:

Subscribers:

Tasks:

Tags:

[ghstack-poisoned]