feat: add FillID() method for Consumer Group

[programmer04]

Adds FillID methods for Consumer Group entities to allow setting deterministic IDs for entities based on their unique properties.

Part of Kong/kubernetes-ingress-controller#4358 (prerequisite)

[codecov-commenter]

Codecov Report

Patch coverage: 45.45% and project coverage change: +0.02 🎉

Comparison is base (5236d86) 52.53% compared to head (73131c8) 52.56%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #357      +/-   ##
==========================================
+ Coverage   52.53%   52.56%   +0.02%     
==========================================
  Files          69       69              
  Lines        5158     5175      +17     
==========================================
+ Hits         2710     2720      +10     
- Misses       1872     1877       +5     
- Partials      576      578       +2     

Flag	Coverage Δ
2.1	36.32% <45.45%> (+0.07%)	⬆️
2.2	47.74% <45.45%> (+0.03%)	⬆️
2.3	48.46% <45.45%> (+0.03%)	⬆️
2.4	48.54% <45.45%> (+0.03%)	⬆️
2.5	48.54% <45.45%> (+0.03%)	⬆️
2.6	48.54% <45.45%> (+0.03%)	⬆️
2.7	50.04% <45.45%> (+0.02%)	⬆️
2.8	50.04% <45.45%> (+0.02%)	⬆️
3.0	50.49% <45.45%> (+0.02%)	⬆️
3.1	51.96% <45.45%> (+0.02%)	⬆️
3.2	52.01% <45.45%> (+0.02%)	⬆️
3.3	52.01% <45.45%> (+0.02%)	⬆️
community	37.99% <45.45%> (+0.06%)	⬆️
enterprise	51.22% <45.45%> (+0.02%)	⬆️
enterprise-nightly	?
integration	52.56% <45.45%> (+0.02%)	⬆️
nightly	37.44% <45.45%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
kong/consumer_group.go	0.00% <0.00%> (ø)
kong/ids.go	59.75% <58.82%> (-0.25%)	⬇️

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