feat: Avm/res/db for postgre sql/flexible server

[josearper]

Description

Closes #1310
Closes #2203
Added new version of PostgreSQL = 16
Also creates a default av zone for waf purposes.

Pipeline Reference

Pipeline

Type of Change

• Update to CI Environment or utilities (Non-module affecting changes)
• [x ] Azure Verified Module updates:
  • [x ] Bugfix containing backwards-compatible bug fixes, and I have NOT bumped the MAJOR or MINOR version in version.json:
    • [x ] 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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