Show user who joined on breakout room in the invitation modal

...components/actions-bar/create-breakout-room/component.jsx

...components/actions-bar/create-breakout-room/container.jsx

...ons-bar/create-breakout-room/sort-user-list/component.jsx

...i/components/actions-bar/create-breakout-room/styles.scss

...button-html5/imports/ui/components/actions-bar/service.js