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 81.45%. Comparing base (07854ab) to head (9ad2a99).
Report is 42 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4600      +/-   ##
==========================================
- Coverage   81.62%   81.45%   -0.17%     
==========================================
  Files         358      359       +1     
  Lines       85674    86568     +894     
==========================================
+ Hits        69929    70512     +583     
- Misses      15745    16056     +311     

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

... and 41 files with indirect coverage changes