Enable gathering requests and responses for tests with a flag.

[Samathy]

I used the fake transport from tests/conftest in my own test code, and needed a reasonable way to enable/disable the gathering of requests and responses for building tests that didn't involve finding and editing wsman.py on my test machine.

[codecov]

Codecov Report

Merging #92 into master will decrease coverage by 0.08%.
The diff coverage is 62.50%.

@@            Coverage Diff             @@
##           master      #92      +/-   ##
==========================================
- Coverage   98.41%   98.32%   -0.09%     
==========================================
  Files          12       12              
  Lines        3284     3292       +8     
==========================================
+ Hits         3232     3237       +5     
- Misses         52       55       +3     

Impacted Files	Coverage Δ
pypsrp/wsman.py	97.45% <62.50%> (-0.66%)	⬇️

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[jborean93]

Unfortunately this isn't something I want to expose publicly as doing so would mean the setup is always there. Maybe there's a better way for your test harness to use the code. You could use monkeypatch to hook into one of the send methods to get the value but I'm not sure if that will work with what you want.