ref: Refactor the modal's UI to be more up to date with BBB

[GuiLeme]

What does this PR do?

It refactors the ui of pick-random-user's modal to be more aligned with bbb and have a more modern design

Motivation

Some design issues were found in the modal.

More

Tests has been refactored (some of them) to embrace this new ui;

See some screenshots ahead:

[gustavotrott]

I think the current "Options" section is mostly about deciding which additional users should participate in the draw. Because of that, it could be simplified into a more direct and intuitive selection list, while also saving UI space.

Instead of:

Options
[] Include moderators
[] Include Presenter
[] Include already picked users

We could use:

Also include:
[] Moderators | [] Presenter | [] Already picked users

This makes the purpose of the section clearer at first glance and keeps the UI more compact.

[gustavotrott]

Adjustments:
"Already picked users" - in plural
"Pick user" - in singular

[gustavotrott]

Idea for the button labels:

• Pick random user
• Pick next random user (or Pick another random user - in case Include already picked user is disabled)
• Quick Pick next random user (for a future button out of the modal)

[gustavotrott]

I suggest to include the time when the user was picked: