[GOV] Private dns zone names sourced dynamically

[LizaShak]

Description

When defining DNS to be used by Private Endpoints, one needs to use specific Private DNS Zone names for the networking to work correctly. For example: to access blobs over private network with a private endpoint a private dns zone named privatelink.blob.core.windows.net is needed.
The names used by those special DNS zones are different in other cloud environments. For example, in the US Goverment cloud one should use privatelink.blob.core.usgovcloudapi.net.

It doesn’t look like AzureRM provider has a capability to help making this “translation” depending on the environment configured for it.

We have an open discussion for it: https://discuss.hashicorp.com/t/private-endpoint-dns-in-different-cloud-environments/50888

So As a Azure TRE Developer
I want to create a mapping for the private dns zone names for the different clouds
So that they are sourced dynamically based on the target cloud type.

Technical Notes:
We have considered two options, but feel free to suggest your own:

1. Create a terraform module and use it across the system
2. Create a local mapping and duplicate it in each terraform

Acceptance criteria

• Design for the mapping and its use
• private dns zone names are taken from the mapping