Add TCPCLv4 message definitions and tcp_reassemble interface

[BrianSipos]

Description

This is a port of earlier TCPCL packet definitions from dtn-demo-agent with more modern scapy-friendly patterns of dispatchers and with a tcp_reassemble() interface.

This is an alternative to part of #4824 with some simplified structures.
Test capture files are included for demonstration.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.41%. Comparing base (56062c6) to head (0e48f49).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5076      +/-   ##
==========================================
+ Coverage   80.09%   80.41%   +0.31%     
==========================================
  Files         375      376       +1     
  Lines       97696    97844     +148     
==========================================
+ Hits        78254    78682     +428     
+ Misses      19442    19162     -280     

Files with missing lines	Coverage Δ
scapy/contrib/tcpcl.py	100.00% <100.00%> (ø)

... and 21 files with indirect coverage changes

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[BrianSipos]

I don't know why the remaining CI job is not passing. I don't see that it relates to the changes in this PR.

[gpotter2]

Hi !

We haven't forgotten you and very sorry for the delay. We have still a few dozens of potential CVEs we need to fix from the Patch the Planet backlog, which is taking longer than expected. Once that is done this is one of our priorities.

Thanks again for the PR and time spent on this !