CLN import from pandas.core.arrays when possible

[JustinZhengBC]

• closes #xxxx
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

pandas.core.arrays.__init__.py imports some classes by default, so other classes can import directly from pandas.core.arrays instead of accessing the specific files

[pep8speaks]

Hello @JustinZhengBC! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/core/arrays/datetimes.py !

• There are no PEP8 issues in the file pandas/core/arrays/period.py !

• There are no PEP8 issues in the file pandas/core/groupby/generic.py !

• There are no PEP8 issues in the file pandas/tests/arrays/test_datetimelike.py !

[jreback]

lgtm. we can merge on green. (

[codecov]

Codecov Report

Merging #23193 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #23193   +/-   ##
=======================================
  Coverage   92.19%   92.19%           
=======================================
  Files         169      169           
  Lines       50964    50964           
=======================================
  Hits        46985    46985           
  Misses       3979     3979

Flag	Coverage Δ
#multiple	90.61% <100%> (ø)	⬆️
#single	42.29% <25%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/core/arrays/period.py	95.56% <100%> (ø)	⬆️
pandas/core/groupby/generic.py	87.06% <100%> (ø)	⬆️
pandas/core/arrays/datetimes.py	97.38% <100%> (ø)	⬆️

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[TomAugspurger]

Green enough :)

Thanks @JustinZhengBC.