terminal-util: tweak any_key_to_proceed() a bit

terminal-util: tweak any_key_to_proceed() a bit

1. Make the message a bit more visible, by adding ANSI color. This
   matters in particular during boot, where the message otherwise might
   be overprinted by other output

2. Let's turn off terminal echo so that whatever key is entered is not
   made visible on screen, and we can handle newline and other keys
   reasonably uniformly.