useless-type-doc issued for undocumented parameters that have PEP484 type annotations

[finite-state-machine]

This likely relates to (and solves) issue #4117.

Steps to reproduce

Call pylint with the docparams extension enabled on the following code:

'''demonstrate FP with useless-type-doc'''

def function(public_param: int, _some_private_param: bool = False) -> None:
    '''does things

    Args:
        public_param: an ordinary parameter
    '''
    for _ in range(public_param):
        ...
    if _some_private_param:
        ...
    else:
        ...

Current behavior

$ python3 -m pylint --load-plugins=pylint.extensions.docparams --rcfile=/dev/null bug.py
************* Module bug
bug.py:4:0: W9020: "_some_private_param" useless ignored parameter type documentation (useless-type-doc)

------------------------------------------------------------------
Your code has been rated at 8.33/10 (previous run: 5.00/10, +3.33)

Expected behavior

Pylint should issue no errors.

It would be reasonable for pylint to issue this error if the type information appeared in the docstring, however, pylint is actually responding to the type annotation (as in PEP484). The docparams module should only issue errors in response to docstrings (or lack thereof), and not PEP484 annotations.

pylint --version output

Result of pylint --version output:

pylint 2.8.1
astroid 2.5.6
Python 3.8.3 (default, Jul  6 2020, 09:12:34)
[Clang 10.0.1 (clang-1001.0.46.4)]