TYP: added missing __init__ in pandas/core/methods
See https://github.com/microsoft/pyright/issues/4544#issuecomment-1407513778


Ruff's INP001 could have caught this. Could enable it if the following are ignored:

> ci/fix_wheels.py:1:1: INP001 File `ci/fix_wheels.py` is part of an implicit namespace package. Add an `__init__.py`.
> ci/test_wheels.py:1:1: INP001 File `ci/test_wheels.py` is part of an implicit namespace package. Add an `__init__.py`.
> doc/make.py:1:1: INP001 File `doc/make.py` is part of an implicit namespace package. Add an `__init__.py`.
> doc/scripts/eval_performance.py:1:1: INP001 File `doc/scripts/eval_performance.py` is part of an implicit namespace package. Add an `__init__.py`.
> doc/source/conf.py:1:1: INP001 File `doc/source/conf.py` is part of an implicit namespace package. Add an `__init__.py`.
> setup.py:1:1: INP001 File `setup.py` is part of an implicit namespace package. Add an `__init__.py`.
> typings/numba.pyi:1:1: INP001 File `typings/numba.pyi` is part of an implicit namespace package. Add an `__init__.py`.
> web/pandas_web.py:1:1: INP001 File `web/pandas_web.py` is part of an implicit namespace package. Add an `__init__.py`.
There are some new errors detected - will try to address or ignore them. The second commit fixes type issues uncovered by a newer pyright version. The third commit uses Sequence[Hashable] more consistently. Looks good just a merge conflict > Looks good just a merge conflict

Rebased and green Thanks @twoertwein 