Support Inband Flow Analyzer (IFA)

[jingfeihu]

1.support IFA over ipv4/ipv6 + udp/tcp/vxlan/gre
2.add IFA unit tests

[codecov]

Codecov Report

Merging #4235 (42c0d26) into master (d71014a) will decrease coverage by 32.66%.
Report is 5 commits behind head on master.
The diff coverage is 36.90%.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4235       +/-   ##
===========================================
- Coverage   81.77%   49.11%   -32.66%     
===========================================
  Files         331      332        +1     
  Lines       76721    76797       +76     
===========================================
- Hits        62736    37718    -25018     
- Misses      13985    39079    +25094     

Files	Coverage Δ
scapy/layers/l2.py	43.33% <20.00%> (-41.81%)	⬇️
scapy/layers/inet.py	24.06% <7.69%> (-46.56%)	⬇️
scapy/contrib/ifa.py	52.83% <52.83%> (ø)

... and 232 files with indirect coverage changes