Fix Emoji picker focus (#7217)

* Only portal the emoji picker where needed

* Add optional portal prop to emoji picker

* Use FocusScope to our advantage

* Pare back, add guards, fix focus trap

* Don't return focus to emoji button

* Set DM input position on emoji insert

* Let the caller determine next focus node

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Co-authored-by: Dan Abramov <dan.abramov@gmail.com>

src/screens/Messages/components/MessagesList.tsx

@@ -101,7 +101,7 @@ export function MessagesList({
   const [emojiPickerState, setEmojiPickerState] =
     React.useState<EmojiPickerState>({
       isOpen: false,
-      pos: {top: 0, left: 0, right: 0, bottom: 0},
+      pos: {top: 0, left: 0, right: 0, bottom: 0, nextFocusRef: null},
     })
 
   // We need to keep track of when the scroll offset is at the bottom of the list to know when to scroll as new items