remove manually created typing d ts file (#249)

* Rename file

".d.ts" files are files that are automatically generated during compilation (in case option is set) and shouldn't be created manually.

* Export types and interfaces

* Add missing imports

src/screens/Sources.tsx

@@ -16,6 +16,7 @@ import { IconButton } from '@mui/material';
 import TravelExploreIcon from '@mui/icons-material/TravelExplore';
 import { useHistory } from 'react-router-dom';
 import { useQuery } from 'util/client';
+import { ISource } from 'typings';
 
 function sourceToLangList(sources: ISource[]) {
     const result: string[] = [];