feat(hooks): add useAssertSingleton

This is copied from the main invokeai repo, with a small change - hook IDs may be symbols.

lib/hooks/use-assert-singleton.ts

@@ -0,0 +1,21 @@
+import { useEffect } from 'react';
+
+const IDS = new Set<string | symbol>();
+
+/**
+ * Asserts that there is only one instance of a singleton entity. It can be a hook or a component.
+ * @param id The unique ID of the singleton entity.
+ */
+export function useAssertSingleton(id: string | symbol) {
+  useEffect(() => {
+    if (IDS.has(id)) {
+      throw new Error(`There should be only one instance of ${String(id)}`);
+    }
+
+    IDS.add(id);
+
+    return () => {
+      IDS.delete(id);
+    };
+  }, [id]);
+}