Add SAE J1939 protocol support to Scapy contrib

[polybassa]

No description provided.

[polybassa]

@BenGardiner Please review.

[codecov]

Codecov Report

❌ Patch coverage is 82.92683% with 42 lines in your changes missing coverage. Please review.
✅ Project coverage is 80.27%. Comparing base (366530e) to head (15d7869).
⚠️ Report is 7 commits behind head on master.

Files with missing lines	Patch %	Lines
scapy/contrib/j1939.py	82.92%	42 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4963      +/-   ##
==========================================
+ Coverage   79.51%   80.27%   +0.76%     
==========================================
  Files         381      383       +2     
  Lines       93716    94595     +879     
==========================================
+ Hits        74521    75939    +1418     
+ Misses      19195    18656     -539     

Files with missing lines	Coverage Δ
scapy/contrib/j1939.py	82.92% <82.92%> (ø)

... and 51 files with indirect coverage changes

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[BenGardiner]

You're gonna need a _Soft_J1939Socket too I think

[BenGardiner]

no soft socket? 😢

A lot of truck analysis happens on a windows platform because that is where it is easiest to use the RP1210 vehicle diagnostic adapters

[polybassa]

no worries. this will be the next PR in this series for J1939. I just want to keep the PRs somewhat "small".

Next step is SoftSocket, followed by a J1939 JsonDB Parser.

I'll fetch your changes from your open PR to the the SoftSocket.

[polybassa]

@gpotter2 This PR is ready from my side. Any feedback?

[gpotter2]

A minor comment, otherwise LGTM.
Thanks

[gpotter2]

Do not hesitate to set socket.XXX if it doesn't exist. It makes it easier to remove the compatibility when eventually we'll reach EOL, and we've been doing that elsewhere (mostly in Windows code)