Add checker for unnecessary ellipsis

[mbyrnepr2]

Current problem

Add a checker for unnecessary ellipsis.

def my_function():
    """docstring & elipses"""
    ...  # nothing emitted

def my_second_function():
    """docstring & pass"""
    pass  # pylint emits: `my_test.py:7:4: W0107: Unnecessary pass statement (unnecessary-pass)`

Desired solution

Emit a warning for this scenario, similar to when a docstring is immediately followed by pass.

Additional context

No response

[Pierre-Sassoulas]

If we implement this the documentation should specify that it's not required when using black.

[mbyrnepr2]

@Pierre-Sassoulas. Thank you for checking this. I don't understand the above comment about how it relates to black, perhaps I am missing something obvious here. Thanks!

[Pierre-Sassoulas]

Ho sorry I made a mistake and it was not very clear. We have a section in the doc where we tell user what message can be disabled when using other linter. I thought black removed unnecessary ellipsis when in fact it does not: I just checked. So this is useful even when using black.

[Pierre-Sassoulas]

My confusion come from the fact that autoflake is removing unecessary pass (not unnecessary ellipsis).