Refactor Command usage and description strings

src/main/java/emu/grasscutter/game/Account.java

@@ -187,6 +187,7 @@ public class Account {
     }
 
     public boolean hasPermission(String permission) {
+        if (permission.isEmpty()) return true;
         if (this.permissions.contains("*") && this.permissions.size() == 1) return true;
 
         // Add default permissions if it doesn't exist