[Bootcamp] Include both python unittest and parser parameters in --help and -h flag...

[Bootcamp] Include both python unittest and parser parameters in --help and -h flag (#64297)

Summary:
Fixes https://github.com/pytorch/pytorch/issues/45945

Creates a new thread to run -h or --help with unittest.main if the help flag is present, and keeps the add_help default for parameters.

Includes both python unittest and parser parameters in --help and -h flag and will remain up to date since both messages are displayed.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/64297

Test Plan:
Imported from GitHub

`python test/test_spectral_ops.py --help`

Output:
```
% python test/test_spectral_ops.py --help
usage: test_spectral_ops.py [-h] [-v] [-q] [--locals] [-f] [-c] [-b] [-k TESTNAMEPATTERNS] [tests [tests ...]]

positional arguments:
  tests                a list of any number of test modules, classes and test methods.

optional arguments:
  -h, --help           show this help message and exit
  -v, --verbose        Verbose output
  -q, --quiet          Quiet output
  --locals             Show local variables in tracebacks
  -f, --failfast       Stop on first fail or error
  -c, --catch          Catch Ctrl-C and display results so far
  -b, --buffer         Buffer stdout and stderr during tests
  -k TESTNAMEPATTERNS  Only run tests which match the given substring

Examples:
  test_spectral_ops.py                           - run default set of tests
  test_spectral_ops.py MyTestSuite               - run suite 'MyTestSuite'
  test_spectral_ops.py MyTestCase.testSomething  - run MyTestCase.testSomething
  test_spectral_ops.py MyTestCase                - run all 'test*' test methods
                                       in MyTestCase

usage: test_spectral_ops.py [-h] [--subprocess] [--seed SEED] [--accept] [--jit_executor JIT_EXECUTOR] [--repeat REPEAT]
                            [--test_bailouts] [--save-xml [SAVE_XML]] [--discover-tests] [--log-suffix LOG_SUFFIX]
                            [--run-parallel RUN_PARALLEL] [--import-slow-tests [IMPORT_SLOW_TESTS]]
                            [--import-disabled-tests [IMPORT_DISABLED_TESTS]]

optional arguments:
  -h, --help            show this help message and exit
  --subprocess          whether to run each test in a subprocess
  --seed SEED
  --accept
  --jit_executor JIT_EXECUTOR
  --repeat REPEAT
  --test_bailouts
  --save-xml [SAVE_XML]
  --discover-tests
  --log-suffix LOG_SUFFIX
  --run-parallel RUN_PARALLEL
  --import-slow-tests [IMPORT_SLOW_TESTS]
  --import-disabled-tests [IMPORT_DISABLED_TESTS]
  ```

Also ran some other tests to make sure tests still worked, and other tests with --help or -h flag

Reviewed By: seemethere

Differential Revision: D30677776

Pulled By: PatrickKan

fbshipit-source-id: eb3d6e3fa677137ec703ec3a23808efb99acc896