fix emoji exploit: sending emoji to self causes game to crash (#1889)

## Description:

When emoji is sent to oneself, it triggers: Cannot send emoji to
oneself: ${this}, because the canSendEmoji wasn't checking if it was
itself.

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

src/core/game/PlayerImpl.ts

@@ -557,6 +557,9 @@ export class PlayerImpl implements Player {
   }
 
   canSendEmoji(recipient: Player | typeof AllPlayers): boolean {
+    if (recipient === this) {
+      return false;
+    }
     const recipientID =
       recipient === AllPlayers ? AllPlayers : recipient.smallID();
     const prevMsgs = this.outgoingEmojis_.filter(