[RULE] Check for public key usage on Linux fleet VM profiles

[BernieWhite]

Existing rule

Azure.VM.PublicKey

Suggested rule

Add support for Microsoft.AzureFleet/fleets with a new rule similar to Azure.VM.PublicKey.

Pillar

Security

Additional context

https://learn.microsoft.com/en-us/azure/templates/microsoft.azurefleet/fleets?pivots=deployment-language-bicep