isort plotting, a handful of test dirs

[jbrockmendel]

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

[pep8speaks]

Hello @jbrockmendel! Thanks for submitting the PR.

• There are no PEP8 issues in the file pandas/plotting/_compat.py !

• There are no PEP8 issues in the file pandas/plotting/_converter.py !

• There are no PEP8 issues in the file pandas/plotting/_core.py !

• There are no PEP8 issues in the file pandas/plotting/_misc.py !

• There are no PEP8 issues in the file pandas/plotting/_style.py !

• There are no PEP8 issues in the file pandas/plotting/_timeseries.py !

• There are no PEP8 issues in the file pandas/plotting/_tools.py !

• There are no PEP8 issues in the file pandas/tests/generic/test_frame.py !

• There are no PEP8 issues in the file pandas/tests/generic/test_generic.py !

• There are no PEP8 issues in the file pandas/tests/generic/test_label_or_level_utils.py !

• There are no PEP8 issues in the file pandas/tests/generic/test_panel.py !

• There are no PEP8 issues in the file pandas/tests/generic/test_series.py !

• There are no PEP8 issues in the file pandas/tests/tseries/offsets/conftest.py !

• There are no PEP8 issues in the file pandas/tests/tseries/offsets/test_fiscal.py !

• There are no PEP8 issues in the file pandas/tests/tseries/offsets/test_offsets.py !

• There are no PEP8 issues in the file pandas/tests/tseries/offsets/test_offsets_properties.py !

• There are no PEP8 issues in the file pandas/tests/tseries/offsets/test_ticks.py !

• There are no PEP8 issues in the file pandas/tests/tseries/offsets/test_yqm_offsets.py !

• There are no PEP8 issues in the file pandas/tests/tseries/test_frequencies.py !

• There are no PEP8 issues in the file pandas/tests/tseries/test_holiday.py !

[codecov]

Codecov Report

Merging #23957 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #23957   +/-   ##
=======================================
  Coverage   92.31%   92.31%           
=======================================
  Files         161      161           
  Lines       51471    51471           
=======================================
  Hits        47515    47515           
  Misses       3956     3956

Flag	Coverage Δ
#multiple	90.7% <100%> (ø)	⬆️
#single	42.43% <86.11%> (ø)	⬆️

Impacted Files	Coverage Δ
pandas/plotting/_style.py	77.41% <100%> (ø)	⬆️
pandas/plotting/_converter.py	63.67% <100%> (ø)	⬆️
pandas/plotting/_tools.py	78.77% <100%> (ø)	⬆️
pandas/plotting/_compat.py	87.5% <100%> (ø)	⬆️
pandas/plotting/_core.py	83.63% <100%> (ø)	⬆️
pandas/plotting/_misc.py	38.68% <100%> (ø)	⬆️
pandas/plotting/_timeseries.py	65.28% <100%> (ø)	⬆️

---

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[jreback]

thanks