Add script for luacheck

[aledbf]

What this PR does / why we need it:

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

[aledbf]

/test pull-ingress-nginx-test

[codecov-io]

Codecov Report

Merging #4287 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4287   +/-   ##
=======================================
  Coverage   58.23%   58.23%           
=======================================
  Files          87       87           
  Lines        6489     6489           
=======================================
  Hits         3779     3779           
  Misses       2282     2282           
  Partials      428      428

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[ElvinEfendi]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, ElvinEfendi

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