feat: changed startNode to use custom type for data

changed to startNode file to be a general file for custom node types, and created a custom type for the data property of StartNode.

BREAKING: renamed StartNode.tsx to NodeDefinitions.tsx

ref: N25B-114

src/visualProgrammingUI/components/NodeDefinitions.tsx

@@ -0,0 +1,22 @@
+import { Handle, Position } from '@xyflow/react';
+import '@xyflow/react/dist/style.css';
+import '../VisProgUI.css';
+
+// Datatypes for NodeTypes
+
+type startNodeData = { label: string; };
+
+// Definitions of Nodes
+
+
+export const StartNode= ({ data } : {data : startNodeData}) => {
+    return (
+        <>
+            <div>
+                <div className="default-node"> data test {data.label} </div>
+                <Handle type="source" position={Position.Right} id="start" />
+            </div>
+        </>
+    );
+};
+export default StartNode;