The support for "use_client_subnet" was half finished.
- Field was defined in schema.
- ResourceData-to-struct code was present but incorrect.
- struct-to-ResourceData code was missing.
Made the change and verified with manual testing:
1. In NS1 UI, switched "Use Client Subnet" between checked and
unchecked.
2. In Terraform config file, switched "use_client_subnet" field between
"true", "false", and omitted.
3. The output of "terraform plan" was as expected in all six cases.
ab18f60071