Feature: Double-tap message to add 👍 reaction

[chrisbobbe]

We've had a support request asking if we might implement double-tap to 👍 react in the Flutter app. Here's the message:

[…] I’d like to ask when the new flutter app would be production ready? And if it can have a double tap to thumbs-up feature. This use case happens incredibly often since my programmers are smart. So usually I just need to drop a hundred thumbs up on their messages to confirm the topic as well as show I’m there. Double tap for thumbs up on a message would simplify life a lot here

Discussion, which includes thoughts on whether this is a feature we'll want to offer. It should be helpful in any case to have this issue in the tracker.

Marking post-launch because this feature doesn't exist in the legacy apps.