Modularisation

You will know more about this topic in the next weeks, but having a background would be good. You need to modularise your app by breaking things into multiple files and keeping utility functions in one place and API handler functions in other.
You can split your [`handler.js`](https://github.com/GSG-G10/AutoComplete/blob/main/src/handler.js) into separate files and end up with a file structure like this:

- handlers\
- publicHandler.js
- homeHandler.js
- searchHandler
- index.js
- utils\
- filter.js
- index.js
- test\
- index.test.js
- router.js
- index.js

Start by reading src/handler.js and identify the utility functions and API handlers it currently contains. Refactor it toward the proposed handlers/ and utils/ structure, then use test/index.test.js to check that the reorganized application still behaves as expected.

Written by the indexing model from the issue text.