Add string sanitisation for proxy-pass-headers & proxy-hide-headers

[shaun-nx]

Proposed changes

This change adds string sanitisation to values provided by both proxy-pass-headers & proxy-hide-headers annotations used by the Ingress resource. This change is being added to prevent the use of special characters in these annotations.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[codecov-commenter]

Codecov Report

Merging #2730 (350fcb1) into main (6681e2c) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2730      +/-   ##
==========================================
- Coverage   53.50%   53.49%   -0.01%     
==========================================
  Files          52       52              
  Lines       14754    14764      +10     
==========================================
+ Hits         7894     7898       +4     
- Misses       6597     6601       +4     
- Partials      263      265       +2     

Impacted Files	Coverage Δ
internal/k8s/validation.go	98.08% <100.00%> (+0.06%)	⬆️
...ternal/k8s/appprotect/app_protect_configuration.go	86.16% <0.00%> (-0.58%)	⬇️
internal/k8s/configuration.go	95.47% <0.00%> (-0.39%)	⬇️

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[jjngx]

👍🏻 great work

[ciarams87]

🚀