Emoji Layout

The emoji keyboard layout will be treated like a language keyboard, in that it shows up in the language switcher popover. The globe button in the bottom left opens that popover.

The emoji keyboard works more or less like the built-in GTK emoji picker. All the emoji are in a single scrollview, split up in categories with headers. At the beginning there's a "frequently used" category. Tapping one of the category icons in the bottom bar navigates to that place in the scrollview, and the category around the current scroll position is always indicated with the blue line active styling.