WIP: feat(etcdutl) add checkv2 and cleanup content

[Elbehery]

Part of #20343

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 164 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.87%. Comparing base (cb7e990) to head (7aadc03).
⚠️ Report is 204 commits behind head on main.

Files with missing lines	Patch %	Lines
etcdutl/etcdutl/check_command.go	0.00%	163 Missing ⚠️
etcdutl/ctl.go	0.00%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
etcdutl/ctl.go	0.00% <0.00%> (ø)
etcdutl/etcdutl/check_command.go	0.00% <0.00%> (ø)

... and 16 files with indirect coverage changes

@@            Coverage Diff             @@
##             main   #20393      +/-   ##
==========================================
- Coverage   69.11%   68.87%   -0.24%     
==========================================
  Files         415      416       +1     
  Lines       34630    34794     +164     
==========================================
+ Hits        23934    23964      +30     
- Misses       9302     9438     +136     
+ Partials     1394     1392       -2     

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