Wrap long strings

[stinodego]

Relates to #4044

I want to improve consistency for line lengths. Because there is a lot to go through, I'm chopping it up in pieces:

• Long strings in the code (this PR)
• Long comments
• Long docstrings

Changes:

• Use black to automatically wrap long strings (this will ensure compliance with black in the future).
• Improve clarity for some of the string wrapping.

[codecov-commenter]

Codecov Report

Merging #4144 (b75082f) into master (2ee2d01) will increase coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #4144      +/-   ##
==========================================
+ Coverage   58.44%   58.47%   +0.02%     
==========================================
  Files         436      436              
  Lines       66888    66888              
==========================================
+ Hits        39092    39110      +18     
+ Misses      27796    27778      -18     

Impacted Files	Coverage Δ
py-polars/polars/internals/construction.py	23.77% <ø> (ø)
py-polars/polars/internals/expr.py	40.95% <ø> (ø)
py-polars/polars/internals/frame.py	27.00% <ø> (ø)
py-polars/polars/internals/lazy_frame.py	26.23% <0.00%> (ø)
py-polars/polars/internals/lazy_functions.py	18.70% <ø> (ø)
py-polars/polars/internals/series.py	36.15% <ø> (ø)
py-polars/polars/internals/slice.py	25.84% <ø> (ø)
py-polars/polars/io.py	16.48% <ø> (ø)
py-polars/polars/testing.py	33.87% <ø> (ø)
py-polars/polars/utils.py	31.91% <ø> (ø)
... and 5 more

---

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[ritchie46]

Yep, seems good to me. Thanks.