BUG: accessor can't access `__name__`

[Zeroto521]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the master branch of pandas.

Reproducible Example

from https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.api.extensions.register_series_accessor.html#pandas.api.extensions.register_series_accessor

import pandas as pd
import numpy as np

@pd.api.extensions.register_dataframe_accessor("geo")
class GeoAccessor:
    def __init__(self, pandas_obj):
        self._obj = pandas_obj

    @property
    def center(self):
        # return the geographic center point of this DataFrame
        lat = self._obj.latitude
        lon = self._obj.longitude
        return (float(lon.mean()), float(lat.mean()))

print(ds.geo.__name__)
# AttributeError: 'GeoAccessor' object has no attribute '__name__'

Issue Description

The instance accessor (ds.geo) doesn't have '__name__' attribute.
But DataFrame.geo.__name__ can get 'GeoAccessor'.

I also tested the Series.str accessor.

>>> import pandas as pd
>>> s = pd.Series('string')
>>> s.str.__name__

C:\Software\miniconda3\lib\site-packages\pandas\core\generic.py in __getattr__(self, name)
   5485         ):
   5486             return self[name]
-> 5487         return object.__getattribute__(self, name)
   5488
   5489     def __setattr__(self, name: str, value) -> None:

AttributeError: 'Series' object has no attribute '__name__'

>>> pd.Series.str.__name__
>>> 'StringMethods'

Expected Behavior

ds.geo.__name__ should return 'GeoAccessor'

Installed Versions

INSTALLED VERSIONS

commit : 66e3805
python : 3.8.12.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.19044
machine : AMD64
processor : Intel64 Family 6 Model 94 Stepping 3, GenuineIntel
byteorder : little
LC_ALL : None
LANG : zh_CN.UTF-8
LOCALE : Chinese (Simplified)_China.936

pandas : 1.3.5
numpy : 1.20.3
pytz : 2021.3
dateutil : 2.8.2
pip : 21.3.1
setuptools : 60.5.0
Cython : 0.29.26
pytest : 6.2.5
hypothesis : None
sphinx : 4.3.2
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : 2.9.3 (dt dec pq3 ext lo64)
jinja2 : 3.0.3
IPython : 7.31.0
pandas_datareader: None
bs4 : 4.10.0
bottleneck : None
fsspec : 2022.01.0
fastparquet : None
gcsfs : None
matplotlib : 3.5.1
numexpr : None
odfpy : None
openpyxl : 3.0.9
pandas_gbq : None
pyarrow : None
pyxlsb : None
s3fs : None
scipy : 1.7.3
sqlalchemy : 1.4.29
tables : None
tabulate : None
xarray : 0.19.0
xlrd : 2.0.1
xlwt : None
numba : 0.54.1