Fixes & cleans up Username input (#2619)

## Description:

**Fix:**
Error box like "Username must be at least 3 characters long" sometimes
still remains after the game starts. See bug report with screenshot:
https://discord.com/channels/1284581928254701718/1449169462426079343/1449169462426079343

This is while in main.ts, element username-validation-error is already
set to hidden. Most of the time this works but apparently sometimes
there's a re-render which removes the 'hidden' tag again. Most probable
solution for this edge case: clear validationError first. Then to make
sure, still hide element username-validation-error.

**Cleanup username.ts:**
- Remove cat and clover emojis from validPattern. For single player
games, the only other validity checks are done from GameRunner calling
sanitize() from Util.ts. And from GameImpl where from addPlayer the
PlayerImpl are created, which uses sanitizeUserName also from
username.ts, which uses validPattern again. Both GameRunner and
PlayerImpl therefor allow emoji. But for muliplayer there's an extra
step where ClientJoinMessageSchema enforces UserNameSchema = SafeString.
Which does NOT allow cat or clover emoji. So for multiplayer you get an
error and can't join a game with cat or clover emoji. To align their
behavior more, just disallow the emojis from validPattern from the
start. Almost no-one ever used them anyway, they were once put in
because a developer liked to use them before the existance of
ClientJoinMessageSchema. There's more consolidation/refactoring possible
but this is an important first step.
- Remove sending arg max: MAX_USERNAME_LENGTH for translation key
invalid_chars, since the translation string doesn't contain params

**Cleanup UserNameInput.ts:**
- Remove userSettings: isn't used anywhere in the code
- Remove dispatchUsernameEvent: nowhere in the repo is event
'username-change' listened to. Also, dispatchUsernameEvent is only
called from connectedCallBack but not anywhere else. It seems like
handleChange was made for this. Also main.ts calls
usernameInput.getCurrentUsername() and doesn't listen for the event
either.

## 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:

tryout33

tests/Censor.test.ts

@@ -105,8 +105,8 @@ describe("username.ts functions", () => {
       const res = validateUsername("Good_Name123");
       expect(res.isValid).toBe(true);
     });
-    test("accepts allowed Unicode like 🐈 or ü", () => {
-      const res = validateUsername("Cat🐈Üser");
+    test("accepts allowed Unicode like ü", () => {
+      const res = validateUsername("Üser");
       expect(res.isValid).toBe(true);
     });
   });
@@ -123,7 +123,7 @@ describe("username.ts functions", () => {
           .slice(0, MAX_USERNAME_LENGTH),
       },
       { input: "", expected: "xxx" },
-      { input: "Ünicode🐈Test!", expected: "Ünicode🐈Test" },
+      { input: "Ünicode Test!", expected: "Ünicode Test" },
     ])('sanitizeUsername("%s") → "%s"', ({ input, expected }) => {
       const out = sanitizeUsername(input);
       expect(out).toBe(expected);