Improve emote suggestion behaviour

[akaminara]

As things currently are, we get emote suggestions even if we only use a single character after :, which makes the use of emotes such as :3 difficult when you want to use them at the end of a message, since you're going to have the suggested emote take its place when you press enter to send.
Instead, it could be a lot more comfortable to have 3 characters behind a : in order for suggestions to appear, or at least 2, so that you don't need to purposefully avoid hitting enter, which is an even bigger issue if, like many people, you're transitioning from Discord over to Revolt.