Add threat intel mode property for applicable firewall resources

[oZakari]

Overview/Summary

Resolves #638
AB#31239
Adds Threat Intelligence Mode property to applicable Azure Firewall resources.

This PR fixes/adds/changes/removes

1. Adds ability to set the threat intelligence mode to either Alert, Deny, or Off.

Breaking Changes

1. No breaking changes as the default value is still the same as before this addition.

Testing Evidence

Replace this with any testing evidence to show that your Pull Request works/fixes as described and planned (include screenshots, if appropriate).

As part of this Pull Request I have

• Read the Contribution Guide and ensured this PR is compliant with the guide
• Ensured the resource API versions in .bicep file/s I am adding/editing are using the latest API version possible
• Checked for duplicate Pull Requests
• Associated it with relevant GitHub Issues
• (ALZ Bicep Core Team Only) Associated it with relevant ADO Items
• Ensured my code/branch is up-to-date with the latest changes in the main branch
• Performed testing and provided evidence.
• Updated one or more of the following tests (if required)
  • Unit
  • Linting
  • E2E (End-To-End)
  • ValidateAzCloud (Base validation in Azure Cloud)
  • ValidateMcCloud (Base validation in Azure China Cloud)
• Updated relevant and associated documentation (e.g. Contribution Guide, Module READMEs, Wiki Docs etc.)
• If relevant, created or updated Code Tours here

[oZakari]

@jtracey93 still need to test so leaving in draft for now.

[jtracey93]

/azp run validateazcloud

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