replace progress circle for zaps with outbox icon

[djschnei21]

taking a stab at #852

[vitorpamplona]

Keep in mind that zap splits are becoming more common and because there could be so many receivers (like 50+ people) the zap progress can become really slow. It might take a whole minute to get all invoices ready for Mutiny. So, just shifting the icon immediately as it starts would leave users without any knowledge of what's happening.

If we want to use a different icon for each stage, I think that icon should also have its own progress bar. Because each stage might take a moment.