Fixed prefill issue for autocomplete field

Related to issue37, as we need to be able to prefill all fields when user decides to start with an existing form

Changes:

• Modified some data structure and related function to make the prefill work.
• Removed some unused import. (Mainly are import React)

Tested with API call. Previous prefill issue for working groups step was fixed. I added the value via MySQL Workbench.

Notice: As we don't have an API call to get all available working groups, so for now when doing the test, the participationLevel need to match this format: [workingGroupID]_level_a such as "jakarta_ee_level_a"