feat: expose serializeNode (#381)

Author: joshbalfour

packages/core/src/index.tsx

@@ -5,4 +5,5 @@ export * from './hooks';
 export * from './editor';
 export * from './events';
 export * from './utils/testHelpers';
+export { serializeNode } from './utils/serializeNode';
 export { ROOT_NODE } from '@craftjs/utils';