[1.26] Import features from ssl module with more granularity

[sethmlarson]

Backport of #2052

[codecov]

Codecov Report

Merging #2053 (77aac9d) into 1.26.x (969fd39) will decrease coverage by 0.52%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##            1.26.x    #2053      +/-   ##
===========================================
- Coverage   100.00%   99.47%   -0.53%     
===========================================
  Files           25       25              
  Lines         2297     2279      -18     
===========================================
- Hits          2297     2267      -30     
- Misses           0       12      +12     

Impacted Files	Coverage Δ
src/urllib3/util/ssl_.py	96.19% <100.00%> (-3.81%)	⬇️
src/urllib3/contrib/_appengine_environ.py	90.00% <0.00%> (-10.00%)	⬇️
src/urllib3/util/wait.py	92.18% <0.00%> (-7.82%)	⬇️
src/urllib3/response.py	99.45% <0.00%> (-0.55%)	⬇️
src/urllib3/util/url.py	100.00% <0.00%> (ø)
src/urllib3/connection.py	100.00% <0.00%> (ø)
src/urllib3/util/retry.py	100.00% <0.00%> (ø)
src/urllib3/util/timeout.py	100.00% <0.00%> (ø)
src/urllib3/util/ssltransport.py	100.00% <0.00%> (ø)

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