Add a check for if statement conditions which are non-empty tuples (#512)

* Add a check for if statement conditions which are non-empty tuples

With the increasing prevalence of wrapping conditionals like:

    if (
        some_value != 'some_condition' and
        other_value is not 42
    )

and for wrapping other constructs with trailing commas, like:

    x = (
        some_value,
        other_value,
    )

it becomes quite easy to accidentally combine these into a
conditional statement which is actually always true:

    if (
        some_value != 'some_condition' and
        other_value is not 42,
    )

This commit introduces a check for such constructs.

* Make this error message make sense

* Further clarity this message's docstring

Co-Authored-By: Ran Benita <ran234@gmail.com>

Co-authored-by: Ran Benita <ran234@gmail.com>