in production, we load secrets/facts from files into environment variables. here, we read the environment variable that corresponds to the identity_service_config file, getting back stringified json. then we try to parse the string directly to an IdentityServiceConfig struct. This is all done inside a lazy_static so that we can access the config easily from the rust-node-addon.
If the env var isn't set or there's an error reading it, we'll fall back on the default value defined in the Default trait implementation of IdentityServiceConfig.
If we get back a JSON string that can't be parsed into an IdentityServiceConfig struct, we will panic, because that means our JSON file is malformed.
I wanted to just use the importJSON function in utils, but that meant either 1. calling js from Rust, which I couldn't figure out how to do, or 2. passing the relevant config to all the functions exposed by the RustAPI, which seemed like a bad practice.