Doc checker quirks

Describe the problem

There are certain quirks which doc checker from #2968 does not handle.

To reproduce place the code below as modin/demo.py and run python scripts/doc_checker modin/demo.py.

The issues are:

1. The script does not handle poor monkey-patching (replacing with lambda without copying a docstring)
2. numpydoc.Validate() reports weird results if identation in Parameters section is too big
3. The script does not point to exact line of failure, but rather to object definition start (makes fixing misspelled moDin in the example below harder)

We should check identation and report it to the user.

Source code / logs

modin/demo.py

def foo(a, b, c):
    """
    Foo mumble mumble.

    moDin is misspelled on purpose.

    Parameters
    ----------
        a : object
            This is description.
        b : object
            More text goes here.
        c : object
            Outta fantasy what to say.

    Returns
    -------
    int
        Random number, generated by fair dice roll.
    """
    return 4


foo = lambda a, b, c: 5

Output when `foo` monkey-patching is active

INFO:PYDOCSTYLE OUTPUT FOR modin\demo.py
ERROR:modin\demo.py:1 at module level:
        D100: Missing docstring in public module
modin\demo.py:1 in public function `foo`:
        D103: Missing docstring in public function

Traceback (most recent call last):
  File "scripts/doc_checker.py", line 557, in <module>
    if not validate(args.paths, args.add_ignore, not args.disable_numpydoc):
  File "scripts/doc_checker.py", line 489, in validate
    if not numpydoc_validate(path):
  File "scripts/doc_checker.py", line 402, in numpydoc_validate
    results = list(map(validate_object, to_validate))
  File "scripts/doc_checker.py", line 328, in validate_object
    noqa_checks = get_noqa_checks(doc)
  File "scripts/doc_checker.py", line 298, in get_noqa_checks
    if "# noqa:" in noqa_str:
TypeError: argument of type 'NoneType' is not iterable

Output when `foo = lambda` is commented out

INFO:PYDOCSTYLE OUTPUT FOR modin\demo.py
ERROR:modin\demo.py:1 at module level:
        D100: Missing docstring in public module

INFO:NUMPYDOC OUTPUT FOR modin\demo.py
ERROR:modin.demo:0:GL08:The object does not have a docstring
ERROR:modin.demo.foo:1:PR01:Parameters {'c', 'b'} not documented
ERROR:modin.demo.foo:1:MD02:Spelling error in line: 3, found: 'moDin', reference: 'Modin'
ERROR:INVALID DOCUMENTATION FOUND

[anmyachev]

Now there is only one way - use # noqa: MD02, but since such a solution disables checking of all words in the dockstring, then in #3001 I will need change regexp pattern.

I have troubles placing # noqa: MD02 correctly. Whenever I put it, it has no effect on the docstring at the beginning of this file. How do you suggest to do it?

To apply to the module documentation, # noqa: MD02 should be placed in the first line of the file.

[vnlitvinov]

The problem has to do with how _inherit_docstrings handle functions with classmethod decorator. cc @vnlitvinov

Tracked by #3033