🚀 [Feature][Webapp] Chat component: ``+`` button open modal to create room

Created by: Elweyn

🚀 Feature

In the chat component the + button has no function yet. Would be nice to have a modal dialog to search a user of the network and open a chat room with him.

🤖 ToDo

• On click on the + button open modal dialog with search of user that has no rooms with self yet.
  • On confirm modal with selected user open a room with the user