test: check flag/docs consistency

[piksel]

This PR adds a test that check whether the flags specified in the code matches the ones in the docs. If either a ENVIRONMENT_VARIABLE or a --argument is not mentioned in the docs it will cause the test to fail.

Note: intentionally pushing the first version of this PR with missing docs.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.20% 🎉

Comparison is base (36391b0) 67.60% compared to head (39547ff) 67.80%.
Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1770      +/-   ##
==========================================
+ Coverage   67.60%   67.80%   +0.20%     
==========================================
  Files          26       26              
  Lines        2380     2395      +15     
==========================================
+ Hits         1609     1624      +15     
  Misses        672      672              
  Partials       99       99              

Files Changed	Coverage Δ
internal/flags/flags.go	85.61% <100.00%> (+0.40%)	⬆️

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