fix: Implement resiliency by default (#3370)

## Description

Default to zone-redundant SKUs
Default to zone-redundant Public IP
fixes #3369 

## Pipeline Reference

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[![avm.res.network.virtual-network-gateway](https://github.com/sebassem/bicep-registry-modules/actions/workflows/avm.res.network.virtual-network-gateway.yml/badge.svg?branch=avm-resiliency-vnetGw)](https://github.com/sebassem/bicep-registry-modules/actions/workflows/avm.res.network.virtual-network-gateway.yml)
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## Type of Change

<!-- Use the checkboxes [x] on the options that are relevant. -->

- [ ] Update to CI Environment or utilities (Non-module affecting
changes)
- [ ] Azure Verified Module updates:
- [X] 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`.
  - [X] Update to documentation

## Checklist

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

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