remove optparse support

[asottile]

been deprecated for 2+ years, time to remove it -- should make reworking this easier

---

here's the error messages that you'll see as well as how to fix things:

you have %default (optparse type) => %(default)s

error:

$ flake8 --help
...
  File "/usr/lib/python3.10/argparse.py", line 642, in _expand_help
    return self._get_help_string(action) % params
TypeError: %d format: a real number is required, not dict

you have type='callback', not really any full replacement

error:

$ flake8 t.py
...
  File "/home/asottile/workspace/flake8/a.py", line 7, in add_options
    parser.add_option(
  File "/home/asottile/workspace/flake8/src/flake8/options/manager.py", line 278, in add_option
    option = Option(*args, **kwargs)
TypeError: Option.__init__() got an unexpected keyword argument 'callback'

you have type='int' => type=int (or other types)

$ flake8 t.py
...
  File "/home/asottile/workspace/flake8/a.py", line 7, in add_options
    parser.add_option("--foo", type="int")
  File "/home/asottile/workspace/flake8/src/flake8/options/manager.py", line 281, in add_option
    self._current_group.add_argument(*option_args, **option_kwargs)
  File "/usr/lib/python3.10/argparse.py", line 1440, in add_argument
    raise ValueError('%r is not callable' % (type_func,))
ValueError: 'int' is not callable