[AVM Module Issue]: ptn/ai-ml/AiFoundry make private dns zone group creation conditional

### Check for previous/existing GitHub issues

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### Issue Type?

Feature Request

### Module Name

avm/ptn/ai-ml/ai-foundry

### (Optional) Module Version

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### Description

Hello All,

I am currently using the ptn/ai-ml/AiFoundry module. I am working in a secure environment that requires that the foundry resources be deployed privately. The environment allows me to deploy private endpoints but does not allow me to create private dns zone groups as this validates policy. The module currently forces me to create private dns zone groups if I have private networked enabled. Can i request that this be made optional? so that users can create private endpoints Only. This is the format for other bicep modules.

thank you

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