[3.8] bpo-39815: add cached_property to all (GH-18726)

[pablogsal]

Automerge-Triggered-By: @pablogsal.
(cherry picked from commit 217dce9)

Co-authored-by: Hakan Çelik [email protected]

https://bugs.python.org/issue39815

[codecov]

Codecov Report

Merging #18728 into 3.8 will increase coverage by 1.19%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##              3.8   #18728       +/-   ##
===========================================
+ Coverage   82.09%   83.28%    +1.19%     
===========================================
  Files        1919     1538      -381     
  Lines      582263   409674   -172589     
  Branches    43739    43739               
===========================================
- Hits       477993   341206   -136787     
+ Misses      94701    58900    -35801     
+ Partials     9569     9568        -1     

Impacted Files	Coverage Δ
Lib/distutils/tests/test_bdist_rpm.py	30.00% <0.00%> (-65.00%)	⬇️
Lib/distutils/command/bdist_rpm.py	7.63% <0.00%> (-56.88%)	⬇️
Lib/test/test_urllib2net.py	76.68% <0.00%> (-13.99%)	⬇️
Lib/test/test_smtpnet.py	78.57% <0.00%> (-7.15%)	⬇️
Lib/ftplib.py	63.72% <0.00%> (-6.08%)	⬇️
Lib/test/test_ftplib.py	87.08% <0.00%> (-4.74%)	⬇️
Tools/scripts/db2pickle.py	17.82% <0.00%> (-3.97%)	⬇️
Lib/test/test_socket.py	72.14% <0.00%> (-3.89%)	⬇️
Tools/scripts/pickle2db.py	16.98% <0.00%> (-3.78%)	⬇️
Lib/test/test_asyncio/test_base_events.py	91.82% <0.00%> (-3.30%)	⬇️
... and 430 more

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