Rewrite the pyOpenSSL implementation in terms of the cryptography one… #159

Job	Run time
Build docs & run doctests	32s
Run linters	31s
Verify dev env (ubuntu-latest)	17s
Type-check package	18s
Tests on 3.8	53s
Verify dev env (windows-latest)	46s
Tests on 3.9	56s
Tests on 3.10	58s
Verify dev env (macos-latest)	23s
Tests on 3.11	1m 3s
Tests on 3.12	1m 9s
Tests on pypy-3.9	1m 8s
Tests on pypy-3.10	1m 10s
Combine & check coverage	7s
Ensure everything required is passing for branch protection	4s
	10m 15s

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