[UI/Logic] Quiz timer

[Nefariusek]

As a user, I want to see a timer, that shows the time since the beginning of a quiz.

Acceptance criteria

Verify, consult and update before starting.

• Clock icon and digits are shown.
• It counts time up in real-time.

Additional notes

• Follow the UI project from miro.
• This functionality should be stored in a separate .js file.