Support Inband Flow Analyzer (IFA)

[jingfeihu]

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

[codecov]

Codecov Report

Attention: Patch coverage is 98.78049% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.23%. Comparing base (1346522) to head (4687de0).

Files with missing lines	Patch %	Lines
scapy/contrib/ifa.py	98.03%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4235      +/-   ##
==========================================
- Coverage   81.62%   81.23%   -0.39%     
==========================================
  Files         359      360       +1     
  Lines       86052    86126      +74     
==========================================
- Hits        70237    69968     -269     
- Misses      15815    16158     +343     

Files with missing lines	Coverage Δ
scapy/layers/inet.py	72.40% <100.00%> (+0.56%)	⬆️
scapy/layers/l2.py	77.01% <100.00%> (-6.75%)	⬇️
scapy/contrib/ifa.py	98.03% <98.03%> (ø)

... and 27 files with indirect coverage changes