Replace User Dropdown with a library that's maintained

[ManuelMoeri]

What to do

While the implementation is perfect (mostly because I did it ) the choices.js library is not being maintained and has a few smaller bugs : )

TODO:

• [ ] Make is searchable like it is now and like it was in the old skills. Which means that strings can be recognized at any point of the name.
• [ ] Search only starts after 2 characters have been entered (Has been removed in the current implementation but could be viable if a clean way can be found)
• [ ] Make sure the dropdown works even when the browser back button is pressed. This is a current problem that has been resolved with some javascript.
• [ ] Re-write tests

If there are any questions

Come to me Ⓜ️Ⓜ️ or just ask robin.

Ticket & Pull request of first Implementation

Ticket: https://github.com/puzzle/skills/issues/637 PR: https://github.com/puzzle/skills/pull/668