Provide more customization options for the service mutator webhook

[diversario]

Issue

• Preserve loadBalancerClass on Service updates #3641
• Allow configuration of webhook selectors aws/eks-charts#1063

Description of changes

For #3641, the webhook configuration needs to support at least operations customization, but being able to exclude certain services by a selector is important for aws/eks-charts#1063.

This PR adds a new section for service mutator webhook configuration. Defaults are set to match the existing configuration, so that this change does not unexpectedly enable service mutation behavior from #3641.

I've not updated the README, want to get feedback first.

Checklist

• Added/modified documentation as required (such as the README.md for modified charts)
• Incremented the chart version in Chart.yaml for the modified chart(s)
• Manually tested. Describe what testing was done in the testing section below
• Make sure the title of the PR is a good description that can go into the release notes

Testing

This change was tested with AWS LBC v2.7.2, and also with AWS LBC built from #3641.

For testing, I had no UPDATE operation first, then I enabled it in the chart.

Tested by creating a Service via kubectl apply, updating it via kubectl apply, and then replacing it via kubectl replace. kubectl replace previously would fail with validation error due to attempt to modify spec.loadBalancerClass. No longer fails.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[k8s-ci-robot]

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[oliviassss]

thanks for the contribution. the change lgtm. can you please add the manual testing you've done on the service mutator webhook in the PR description? thanks.

[diversario]

thanks for the contribution. the change lgtm. can you please add the manual testing you've done on the service mutator webhook in the PR description? thanks.

Updated description.

[oliviassss]

/ok-to-test

[oliviassss]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: diversario, oliviassss

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