New command "Wait until WiFi"

[Lars-]

I would have liked to build this myself and send a pull request for this enhancement, but I have no clue in which repo to do it...

Since it takes a while to connect to WiFi, it would be amazing if there was a command like "Wait for WiFi" when turning on an activity. Now I need to add a delay of 2 seconds even though this is sometimes too short and sometimes completely unnecessary.