And move canonicalized_path() to a static method on LexicalPath.
This is to make it clear that FileSystemPath/canonicalized_path() only
perform *lexical* canonicalization.
Widgets can now opt in to emoji input via set_accepts_emoji_input().
If the focused widget accepts emoji input, we'll pop up a simple dialog
with all the available emojis as clickable buttons.
You can press escape if you change your mind and don't want an emoji.
This UI layout definitely will not scale as we add more emojis, but it
works for the moment, and we can adapt it as we go. Pretty cool! :^)
