Raised in D5463, the web app should behave as the native app:

• when selecting someone in the chat composer who isn't a friend, and when nobody else is selected, the web app should exit search and create a 1-1 thread with this user
• should display alert if you try to add a non-friend when you have already selected some users
• should display alert on blocked users

Depends on D5463

Alerts (text is the same as in the native app):

• select a friend, create chat
• select a non-friend -> search should end and chat should be displayed without the search bar
• select a friend, than a non-friend -> alert should be displayed
• select a blocked user -> alert should be displayed