fix: export flyout from package root (#2103)

Author: chrisdholt

packages/fast-components-react-msft/src/index.ts

@@ -17,6 +17,7 @@ export * from "./context-menu-item";
 export * from "./dialog";
 export * from "./divider";
 export * from "./flipper";
+export * from "./flyout";
 export * from "./heading";
 export * from "./hypertext";
 export * from "./image";