Group-level IP allowlist cannot be managed via API

There does not appear to be an API endpoint for managing the list of IP ranges when using the "Restrict group access by IP address" feature. This also implies that it cannot be managed via our Terraform provider.

This makes management of the allowlist by customers with large internal networks a manual and error-prone process. In particular, it can be difficult for administrators to identity and correctly remove IP ranges when they are looking at a list containing 100s of elements in the UI.