Set default syntax and UI hint for Predicate input

Added `DefaultSyntax` and `UIHint` properties to the Predicate input field in the MessageReceived activity. This change ensures the input field is configured for JavaScript syntax and provides an expression editor for better user experience.

src/modules/Elsa.Kafka/Activities/MessageReceived.cs

@@ -49,7 +49,9 @@ public class MessageReceived : Trigger<object>
 
     [Input(
         Description = "Optional. A predicate to filter messages.",
-        AutoEvaluate = false
+        AutoEvaluate = false,
+        DefaultSyntax = "JavaScript",
+        UIHint = InputUIHints.ExpressionEditor
     )]
     public Input<bool> Predicate { get; set; } = default!;