[Module Proposal]: `avm-res-aad-domainservice`

### Check for previous/existing GitHub issues/module proposals

- [X] I have checked for previous/existing GitHub issues/module proposals.

### Check this module doesn't already exist in the module indexes

- [X] I have checked for that this module doesn't already exist in the module indexes.

### Bicep or Terraform?

Terraform

### Module Classification?

Resource Module

### Module Name

avm-res-aad-domainservice

### Module Details

AVM Resource Module for Azure Active Directory Domain Service

### Do you want to be the owner of this module?

No

### Module Owner's GitHub Username (handle)

_No response_

### (Optional) Secondary Module Owner's GitHub Username (handle)

_No response_

No file, test, or entry point is named. Start by reviewing the Terraform module indexes and existing resource modules to determine the expected shape for avm-res-aad-domainservice; done would mean the proposed Azure Active Directory Domain Service module is implemented and added to the appropriate index.

Written by the indexing model from the issue text.