Add validation for wildcard server names

[aledbf]

What this PR does / why we need it:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Which issue/s this PR fixes

From NGINX docs

The name “*.example.org” matches not only www.example.org but www.sub.example.org as well.

This is not valid. We should validate only one level is configured.

How Has This Been Tested?

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have added tests to cover my changes.
• All new and existing tests passed.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf

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• OWNERS [aledbf]

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[codecov-io]

Codecov Report

Merging #6348 into master will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #6348      +/-   ##
==========================================
+ Coverage   55.81%   55.85%   +0.03%     
==========================================
  Files          89       89              
  Lines        6358     6363       +5     
==========================================
+ Hits         3549     3554       +5     
  Misses       2369     2369              
  Partials      440      440              

Impacted Files	Coverage Δ
internal/ingress/controller/nginx.go	28.91% <ø> (ø)
internal/ingress/controller/template/template.go	77.27% <100.00%> (+0.16%)	⬆️

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[aledbf]

/assign @ElvinEfendi

[aledbf]

After this PR only two tests fail

https://aledbf.github.io/ingress-conformance-sample/index.html