output/csv: Revert the JSON names of the config

[codebien]

What?

Restore the output/csv config to use the snake_case for the JSON names #3390 (comment). It keeps the changes related to the CLI flags.

Why?

The breaking change would introduce some risks that we have to analyze better.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make ci-like-lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

#3390

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (e8886ac) 73.13% compared to head (0b6890e) 73.13%.

❗ Current head 0b6890e differs from pull request most recent head 18e1b01. Consider uploading reports for the commit 18e1b01 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3395   +/-   ##
=======================================
  Coverage   73.13%   73.13%           
=======================================
  Files         258      258           
  Lines       19642    19642           
=======================================
  Hits        14365    14365           
  Misses       4395     4395           
  Partials      882      882           

Flag	Coverage Δ
ubuntu	73.06% <ø> (-0.02%)	⬇️
windows	72.96% <ø> (-0.02%)	⬇️

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

Files	Coverage Δ
output/csv/config.go	74.50% <ø> (ø)

... and 2 files with indirect coverage changes

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