Info bar about bridge configuration

Everybody we had to configure a bridge was confused about the fact that the bridge information was not entered in the Greeter and was worried about having made a mistake. We can’t really change this now as that’s a much more complex issue but for the time being we could add an info bar in the Greeter saying that the actual configuration will be done later on.

Feature Branch: greeter:feature/revamp_phase1

Parent Task: #10812 (closed)

Original created by @alant on 10825 (Redmine)