Solved issue 45: Add optional private endpoints for AI Services and Storage Accounts

[rliberoff]

This PR would solve issue #45.

All private endpoints are set when the new variable use_private_endpoints is true. Also, the current IP address of the machine executing these templates is used as an allowed IP address to facilitate managing these services.

• Increased the size of the subnet for Private Endpoints, from /29 to /28 since currently near 9 services requires them.
• Increased the size of the subnet for the APIM to /27 as recommended by Microsoft's documentation.
  • Also, added delegation in the subnet for the APIM as specified by Microsoft's documentation.
• Added support for private endpoints and related variables in Azure AI Search module.
• Added support for private endpoints and related variables in OpenAI module.
• Added support for private endpoints and related variables in Document Intelligence (a.k.a. Forms) module.
• Added support for private endpoints and related variables in Cognitive Services module.
• Added support for private endpoints and related variables for Storage Account services.
• Now the Azure API Management is deployed with (External) VNet support when the use_private_endpoints variable is set to true.

[rliberoff]

Change the private DNS zone names and we'll be read to merge 🎉🎉🎉

Done. Changed as agreed!