feat: added alerts for key kault certificates nearing or past expiry

[nc-shahidazim]

Description

This PR implements alerting for near‑expiry and expired Azure Key Vault certificates 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 expired certificates.

Context

Managing certificate lifecycles is critical for maintaining application security and avoiding unexpected outages caused by expired Key Vault certificates. While Azure Key Vault emits events for CertificateNearExpiry and CertificateExpired, 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 certificate rotation.

What’s Included

• Added scheduled query alerts to capture CertificateExpired and CertificateNearExpiry events from Key Vault.
• Implemented KQL logic to surface relevant certificate 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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