Added onInit and useInitialized hooks

packages/svelte/src/lib/hooks/useInitialized.ts

@@ -0,0 +1,28 @@
+import { useStore } from '$lib/store';
+
+/**
+ * Hook for seeing if nodes are initialized
+ * @returns - nodesInitialized Writable
+ */
+export function useNodesInitialized() {
+  const { nodesInitialized } = useStore();
+  return nodesInitialized;
+}
+
+/**
+ * Hook for seeing if edges are initialized
+ * @returns - edgesInitialized Writable
+ */
+export function useEdgesInitialized() {
+  const { edgesInitialized } = useStore();
+  return edgesInitialized;
+}
+
+/**
+ * Hook for seeing if the flow is initialized
+ * @returns - initialized Writable
+ */
+export function useInitialized() {
+  const { initialized } = useStore();
+  return initialized;
+}