emergency-menu: Improve placeholder page

Use a dimmed status page when the list is empty.

@snwh this also works around the incorrect styling of the last entry in the emergency contacts list (triggered by the placeholder page), see topmost commit. Overall it looks to the page could be improved to make the separation between the owners name ((here agx), the title (Emergency contacts) and the content (either placeholder or listbox) more prominent. @snwh would that be somthing for you to look at as a follow up?

/cc @CoderThomasB