Implement CLI

[ScandiumSG]

Make the CLI interface

Ask for 2 currencies and an input amount for the first currency and convert using the latest available conversion rate stored in the db

• [x] Setup CLI
• [x] Perform and output calculation

[ScandiumSG]

Preliminary version added in 966e444444960a5e1f7a7f86647f6ce3016b23ca

Combined with some api changes: time spent 45min

[ScandiumSG]

spent 50min ish improving CLI + some docker config troubleshooting

Closing since the calculation placeholder in the endpoint is returned and displayed.