Fetch project-specific values from config file(s)

- [ ] Fetch [`token_address`](https://github.com/nation3/nationcred-instance/blob/main/generate-csv.js#L69) from `currencyDetails.json`
- [ ] Fetch [`floor`](https://github.com/nation3/nationcred-instance/blob/main/generate-csv.js#L75) value from `grain.json`