feat: added alerts for Key Vault secrets nearing or past expiry

[nc-shahidazim]

Description

This PR implements alerting for near‑expiry and expired Azure Key Vault secrets using scheduled query alerts. It detects Key Vault event records from AzureDiagnostics and routes notifications through existing Action Groups. The goal is to strengthen operational awareness and prevent service interruptions due to unrotated secrets.

Context

Managing secret lifecycles is critical for maintaining application security and avoiding unexpected outages caused by expired Key Vault secrets. While Azure Key Vault emits events for SecretNearExpiry and SecretExpired, no alerting mechanism was previously in place to surface these events to engineering teams. This PR introduces automated alerting based on these system events to improve visibility and ensure proactive secret rotation.

What’s Included

• Added scheduled query alerts to capture SecretExpired and SecretNearExpiry events from Key Vault.
• Implemented KQL logic to surface relevant secret metadata from AzureDiagnostics.
• Integrated Action Group notifications to deliver timely alerts to the team.
• Added configuration options for evaluation frequency and alert window.

Type of changes

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

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

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Sensitive Information Declaration

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• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[rfk-nc]

Nice :)