capture: improve typing

[bluetech]

I'm looking at improving the capture plugin again, but first I thought I'd finish the typing. Adds some verbosity but needed to "capture" the current usage.

Might be easier to review commit by commit.

[nicoddemus]

LGTM!

Just have to adapt some of the unsupported features for Python 3.8/3.7. 👍

[bluetech]

@nicoddemus Thanks for the notes, fixed. Also fixed the coverage.

[hroncok]

Is it possible that this broke some assumptions? Namely, I see this error in click:

==================================== ERRORS ====================================
_____________________ ERROR at teardown of test_bytes_args _____________________
/usr/lib/python3.11/site-packages/_pytest/runner.py:341: in from_call
    result: Optional[TResult] = func()
/usr/lib/python3.11/site-packages/_pytest/runner.py:262: in <lambda>
    lambda: ihook(item=item, **kwds), when=when, reraise=reraise
/usr/lib/python3.11/site-packages/pluggy/_hooks.py:265: in __call__
    return self._hookexec(self.name, self.get_hookimpls(), kwargs, firstresult)
/usr/lib/python3.11/site-packages/pluggy/_manager.py:80: in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
/usr/lib/python3.11/site-packages/_pytest/runner.py:182: in pytest_runtest_teardown
    item.session._setupstate.teardown_exact(nextitem)
/usr/lib/python3.11/site-packages/_pytest/runner.py:537: in teardown_exact
    raise exceptions[0]
/usr/lib/python3.11/site-packages/_pytest/runner.py:526: in teardown_exact
    fin()
/usr/lib/python3.11/site-packages/_pytest/fixtures.py:686: in <lambda>
    subrequest.node.addfinalizer(lambda: fixturedef.finish(request=subrequest))
/usr/lib/python3.11/site-packages/_pytest/fixtures.py:1038: in finish
    raise exc
/usr/lib/python3.11/site-packages/_pytest/fixtures.py:1031: in finish
    func()
/usr/lib/python3.11/site-packages/_pytest/fixtures.py:918: in _teardown_yield_fixture
    next(it)
/usr/lib/python3.11/site-packages/_pytest/monkeypatch.py:55: in monkeypatch
    mpatch.undo()
/usr/lib/python3.11/site-packages/_pytest/monkeypatch.py:397: in undo
    setattr(obj, name, value)
E   AttributeError: property 'encoding' of 'DontReadFromInput' object has no setter
=================================== FAILURES ===================================
_______________________________ test_bytes_args ________________________________
tests/test_arguments.py:89: in test_bytes_args
    monkeypatch.setattr(sys.stdin, "encoding", "utf-8")
E   AttributeError: property 'encoding' of 'DontReadFromInput' object has no setter
=========================== short test summary info ============================
FAILED tests/test_arguments.py::test_bytes_args - AttributeError: property 'e...
ERROR tests/test_arguments.py::test_bytes_args - AttributeError: property 'en...