Feat: add mechanism to check cancellation in Agent (#10766)

### What problem does this PR solve?

Add mechanism to check cancellation in Agent.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

agent/component/begin.py

@@ -37,7 +37,13 @@ class Begin(UserFillUp):
     component_name = "Begin"
 
     def _invoke(self, **kwargs):
+        if self.check_if_canceled("Begin processing"):
+            return
+
         for k, v in kwargs.get("inputs", {}).items():
+            if self.check_if_canceled("Begin processing"):
+                return
+
             if isinstance(v, dict) and v.get("type", "").lower().find("file") >=0:
                 if v.get("optional") and v.get("value", None) is None:
                     v = None