Separate check for possibly unused variables if locals() is used

[danijar]

It would be great to have a separate check for unused variables if locals() is used in the same scope:

def example_no_locals():
  value = 42  # pylint: disable=unused-variable

def exmaple_defined_before():
  value = 42  # pylint: disable=possibly-unused-variable
  print(locals())

def exmaple_defined_after():
  print(locals())
  value = 42  # pylint: disable=unused-variable

The benefit of this is that one can disable probably-unused-variable for a file (that has a lot of string formatting in it, or the config code example in #641) or the whole project without also loosing checks for unused-variable.

[danijar]

@PCManticore Thanks a lot for working on this!