feat: introduce trigger functionality (#27644)

Signed-off-by: lyzno1 <yuanyouhuilyz@gmail.com>
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api/core/workflow/graph/graph.py

@@ -117,7 +117,7 @@ class Graph:
             node_type = node_data.get("type")
             if not isinstance(node_type, str):
                 continue
-            if node_type in [NodeType.START, NodeType.DATASOURCE]:
+            if NodeType(node_type).is_start_node:
                 start_node_id = nid
                 break