detect/integers: add support for negated strings when enum is used - v3

[AkakiAlice]

Ticket: #7513

Contribution style:

• I have read the contributing guide lines at
  https://docs.suricata.io/en/latest/devguide/contributing/contribution-process.html

Our Contribution agreements:

• I have signed the Open Information Security Foundation contribution agreement at
  https://suricata.io/about/contribution-agreement/ (note: this is only required once)

Changes (if applicable):

• I have updated the User Guide (in doc/userguide/) to reflect the changes made
• I have updated the JSON schema (in etc/schema.json) to reflect all logging changes
  (including schema descriptions)
• I have created a ticket at
  https://redmine.openinfosecfoundation.org/issues/7513

Link to ticket: https://redmine.openinfosecfoundation.org/issues/7513

uint.rs changes:

• add comment and simpler syntax: line 68

integer-keywords.rst changes:

• document the usage of negated strings when using enum: line 58, line 66

SV_BRANCH=OISF/suricata-verify#2257
Previous PR = #12453

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.54%. Comparing base (d63ad75) to head (3613946).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #12484      +/-   ##
==========================================
+ Coverage   80.52%   80.54%   +0.01%     
==========================================
  Files         923      923              
  Lines      259176   259182       +6     
==========================================
+ Hits       208708   208764      +56     
+ Misses      50468    50418      -50     

Flag	Coverage Δ
fuzzcorpus	56.15% <80.00%> (+0.09%)	⬆️
livemode	19.38% <0.00%> (-0.04%)	⬇️
pcap	44.20% <0.00%> (+<0.01%)	⬆️
suricata-verify	63.32% <100.00%> (-0.01%)	⬇️
unittests	58.44% <80.00%> (-0.01%)	⬇️

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