Create client module + country client

[ownerofglory]

1. create a new mvn module named hillel-trip-planner-client groupId: same as parent artifactId: hillel-trip-planner-client version: same as parent
2. Create a REST client that consumes following endpoints:
   • all country names
   • country data by its name
3. Create needed DTO classes
4. Register client as a Spring component
5. Important: Consider optimizing the API usage (caching, omitting optional attributes, etc.)

You can use following REST API provider https://restcountries.com/#endpoints-all

[ownerofglory]

Here is why we may wanna use it