Typing Cleanup - Remove Blacklisted Items
#25844 introduced a blacklist of modules in the mypy.ini config file which currently throw errors when analyzed with mypy. We would ideally be able to whittle these down (save exclusion of the test folder(s), which I think is fine).

I'm not sure there is one easy way to split it up as the degree of difficulty may vary wildly. PRs from the community to clean up one to a few of the blacklisted modules at a time would certainly be welcome!

Here's the list of modules for reference:

- [X] pandas._config.config (#25899)
- [X] pandas._version (#25949)
- [X] pandas.compat (#26251)
- [X] pandas.compat.numpy.function
- [X] pandas.compat.pickle_compat (#25991)
- [X] pandas.core.accessor (#26146)
- [x] pandas.core.api
- [X] pandas.core.apply
- [X] pandas.core.arrays.array_  (#26065)
- [X] pandas.core.arrays.datetimelike  (#26065)
- [X] pandas.core.arrays.integer  (#26065)
- [X] pandas.core.arrays.interval (#26065)
- [X] pandas.core.arrays.numpy_ (#26065)
- [X] pandas.core.arrays.period (#26065)
- [X] pandas.core.arrays.sparse (#26065)
- [X] pandas.core.arrays.timedeltas (#26065)
- [x] pandas.core.base
- [x] pandas.core.computation.expr
- [x] pandas.core.computation.ops
- [x] pandas.core.computation.pytables
- [x] pandas.core.config (#26048)
- [x] pandas.core.config_init
- [X] pandas.core.dtypes.dtypes (#26028)
- [X] pandas.core.dtypes.missing (#26028)
- [X] pandas.core.frame
- [X] pandas.core.generic
- [X] pandas.core.groupby.generic (#26089)
- [X] pandas.core.groupby.groupby (#26089)
- [X] pandas.core.groupby.ops (#26089)
- [x] pandas.core.indexes.base (#26315)
- [x] pandas.core.indexes.datetimelike
- [ ] pandas.core.indexes.datetimes (#26315)
- [x] pandas.core.indexes.period (#26315)
- [x] pandas.core.indexes.timedeltas (#26315)
- [x] pandas.core.indexing
- [x] pandas.core.internals.blocks
- [x] pandas.core.ops
- [X] pandas.core.panel (DEPRECATED - do not update)
- [x] pandas.core.resample
- [X] pandas.core.reshape.concat (#26019)
- [x] pandas.core.reshape.merge
- [x] pandas.core.reshape.reshape
- [X] pandas.core.reshape.tile (#26019)
- [X] pandas.core.series
- [X] pandas.core.sparse.frame
- [X] pandas.core.strings (#25902)
- [x] pandas.core.util.hashing
- [x] pandas.core.window
- [x] pandas.io.clipboards (#26048)
- [x] pandas.io.feather_format (#25939)
- [x] pandas.io.formats.css (#25900)
- [x] pandas.io.html (#25939)
- [x] pandas.io.json.json (#25939)
- [x] pandas.io.json.normalize (#25939)
- [x] pandas.io.json.table_schema (#25939)
- [x] pandas.io.packers (#25939)
- [x] pandas.io.parquet (#25939)
- [x] pandas.io.pytables
- [x] pandas.io.stata (#25940)
- [X] pandas.plotting._core (#26021)
- [X] pandas.tseries.frequencies (#26014)
- [X] pandas.tseries.holiday (#26014)
- [X] pandas.tseries.offsets (#26014)
- [x] pandas.util._doctools
- [x] pandas.util.testing