Add support for more ISAKMP payloads

[dmaciejak]

Adding support for Nonce, Hash, Sig and KE payloads. Took also the chance to update the NotifyMessageType.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.69%. Comparing base (07854ab) to head (b2345e6).
Report is 30 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4600      +/-   ##
==========================================
+ Coverage   81.62%   81.69%   +0.07%     
==========================================
  Files         358      359       +1     
  Lines       85674    86685    +1011     
==========================================
+ Hits        69929    70815     +886     
- Misses      15745    15870     +125     

Files with missing lines	Coverage Δ
scapy/layers/isakmp.py	89.18% <100.00%> (+0.68%)	⬆️

... and 26 files with indirect coverage changes