Azure AD Admin needs to be imported into state when deploying Azure PostgreSQL server with geo-restore

When deploying a resource azurerm_postgresql_server with create_mode set to GeoRestore Azure will assign the same Azure AD Admin to the target server, as was assigned to the source server. This causes deployment to fail when trying to assign azurerm_postgresql_active_directory_administrator to the target server because Terraform tries to create the Azure AD admin because Terraform thinks the AAD Admin is not configured on the target server, but Azure created it while restoring from backup.

Terraform needs to support importing the azurerm_postgresql_active_directory_administrator resource automatically when performing geo-restore deployment.