feat: support Istio add-on in AKS

[fsforza]

Description

This Pull Request enable Istio add-on on AKS. Following features are enabled:

• Istio Revisions Selection
• Internal Ingress Gateway
• External Ingress Gateway
• Plug your own CA from Key Vault

Closes #3363

Pipeline Reference

Pipeline

Type of Change

• Update to CI Environment or utilities (Non-module affecting changes)
• Azure Verified Module updates:
  • Bugfix containing backwards-compatible bug fixes, and I have NOT bumped the MAJOR or MINOR version in version.json:
    • Someone has opened a bug report issue, and I have included "Closes #{bug_report_issue_number}" in the PR description.
    • The bug was found by the module author, and no one has opened an issue to report it yet.
  • Feature update backwards compatible feature updates, and I have bumped the MINOR version in version.json.
  • Breaking changes and I have bumped the MAJOR version in version.json.
  • Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• I have run Set-AVMModule locally to generate the supporting module files.
• My corresponding pipelines / checks run clean and green without any errors or warnings

[fsforza]

@microsoft-github-policy-service agree

[eriqua]

Thanks a lot @fsforza for quickly addressing the above comments!
The scope of the change is now at module level, therefore the module owner can take the review further.
@ilhaan @JPEasier FYI

[eriqua]

Hey @ilhaan, @JPEasier just a heads up to have a look at this PR when you have some availability. Thanks!

[JPEasier]

Looks good for me!
Thank you for your contribution @fsforza 🚀