Add Admin Opcode 25 : Send Server Messages (#19)

* Add Admin Code 25 : XSS Message As Server (why?)

Added the ability to send messages from the server name (without username), with XSS. 
Accepts 1 string argument : message text

* remove redundant switch statement and add check for msgArr length

---------

Co-authored-by: Elijah R <62162399+elijahr2411@users.noreply.github.com>

src/WSServer.ts

@@ -681,6 +681,12 @@ export default class WSServer {
                                 break;
                         }
                         break;
+                        case "25":
+                            if (client.rank !== Rank.Admin || msgArr.length !== 3)
+                                return;
+                            this.clients.forEach(c => c.sendMsg(guacutils.encode("chat", "", msgArr[2])));
+                        break;
+                        
                 }
                 break;