Service improvements

[sasastevcic]

• [x] Move api key to the env variable
• [x] Create base url constant
• [x] Add error handling with try/catch
• [x] Move the service to its own folder src/service/NewsService.ts and rename the file to be singular "Service"
• [x] Create an Article type and use it as the return type of functions. Also reuse it across the app, where needed

[markanns]

done