Add json-dap command line and debug options

[karthiknadig]

Fixes #1460

[fabioz]

Seeing this review got me thinking a bit about how we want to approach having pydevd out of process...

I think we'll want to keep the ptvsd namespace for users (for the current public API), so, a part of ptvsd will still be builtin into the same process pydevd and could use pydevd in the namespace and that could be a good place to customize what we need without needing to add arguments nor environment variables.

So, maybe a better approach could be:

Create a pydevd_defaults.py module which would be the place for flags we want to customize (right next to pydevd_constants.py) with:

from _pydevd_bundle.pydevd_constants import QUOTED_LINE_PROTOCOL

class PydevdCustomization(object):
    DEFAULT_PROTOCOL = QUOTED_LINE_PROTOCOL

and in the PyDB constructor, instead of checking the environment variable, just do:

PyDevdAPI().set_protocol(self, PydevdCustomization.DEFAULT_PROTOCOL)

and in force_pydevd.py

PydevdCustomization.DEFAULT_PROTOCOL = JSON_PROTOCOL

In that case we wouldn't need the handling of the arguments nor the environment variable... what do you think?

[karthiknadig]

@fabioz I like the idea using pydevd_defaults.py, i don't like the environment variable approach here. I will switch to that. But I also feel --json-dap should be supported. There are several other debugger options enabled this way. Given this is fundamental part of how pydevd will work going forward I feel it is a must have.

[karthiknadig]

The 2.7 failure on windows seems to be the result of tox 3.12.0 that was released today. Likely there will be a patch.

py27
GLOB sdist-make: D:\a\1\s\setup.py
Traceback (most recent call last):
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\runpy.py", line 72, in _run_code
    exec code in run_globals
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\__main__.py", line 4, in <module>
    tox.cmdline()
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\session\__init__.py", line 44, in cmdline
    main(args)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\session\__init__.py", line 68, in main
    exit_code = session.runcommand()
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\session\__init__.py", line 192, in runcommand
    return self.subcommand_test()
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\session\__init__.py", line 208, in subcommand_test
    venv.package = self.hook.tox_package(session=self, venv=venv)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\pluggy\hooks.py", line 289, in __call__
    return self._hookexec(self, self.get_hookimpls(), kwargs)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\pluggy\manager.py", line 68, in _hookexec
    return self._inner_hookexec(hook, methods, kwargs)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\pluggy\manager.py", line 62, in <lambda>
    firstresult=hook.spec.opts.get("firstresult") if hook.spec else False,
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\pluggy\callers.py", line 208, in _multicall
    return outcome.get_result()
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\pluggy\callers.py", line 81, in get_result
    _reraise(*ex)  # noqa
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\pluggy\callers.py", line 187, in _multicall
    res = hook_impl.function(*args)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\package\__init__.py", line 16, in tox_package
    session.package, session.dist = get_package(session)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\package\__init__.py", line 29, in get_package
    package = acquire_package(config, session)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\package\__init__.py", line 40, in acquire_package
    path = build_package(config, session)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\package\builder\__init__.py", line 7, in build_package
    return make_sdist(config, session)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\package\builder\legacy.py", line 29, in make_sdist
    returnout=True,
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\site-packages\tox\action.py", line 93, in popen
    else 0
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\subprocess.py", line 390, in __init__
    errread, errwrite)
  File "C:\hostedtoolcache\windows\Python\2.7.14\x64\lib\subprocess.py", line 640, in _execute_child
    startupinfo)
TypeError: environment can only contain strings