Test the CLI command

Assuming that the CLI command was going to be very static, I've been just testing all conditions manually. We do appear to be [adjusting](https://github.com/api3dao/contracts/pull/360) it though, so automated tests would be nice. I would refer to [airnode-admin e2e tests](https://github.com/api3dao/airnode/tree/master/packages/airnode-admin/test/e2e) for how that could be done.