feat: support appState.exportEmbedScene to embed scene data in exportToSvg util (#3777)

* feat: add embedScene attribute to exportToSvg util

* fix

* return promise

* add docs and remove

* fix

* fix tests

* use

* fix

* fix

* remove metadata and use exportEmbedScene

* fix

* fix

* fix

* fix

* IIFE

src/data/json.ts

@@ -15,7 +15,7 @@ import Library from "./library";
 
 export const serializeAsJSON = (
   elements: readonly ExcalidrawElement[],
-  appState: AppState,
+  appState: Partial<AppState>,
 ): string => {
   const data: ExportedDataState = {
     type: EXPORT_DATA_TYPES.excalidraw,