New emoji selector problems

There are 2 problems with this new design:

1. We are not tracking emojis as "frequently used emojis" when they are selected for reactions, only when they are chosen in the post composer, so it doesn't actually work right. To fix, track emojis when they're used in reacts.
2. "Like" is not actually an emoji, so it can never be in the list, even though it probably should be. I think to fix this, we should force the thumbs-up like to always be in the list regardless of frequency or admin settings.