Pre-suppress unused-promise lint errors in xplat/js (#36590)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/36590

Pre-suppress unused-promise lint errors in xplat/js. The next diff enables the lint.

See https://flow.org/en/docs/linting/rule-reference/#toc-unused-promise for more details.

Changelog: [Internal]

drop-conflicts
bypass-lint

Reviewed By: pieterv

Differential Revision: D43967290

fbshipit-source-id: f36242a732dbc18bf7482adfb46ca2b77e1b1493

packages/rn-tester/js/examples/ScrollView/ScrollViewExample.js

@@ -741,6 +741,7 @@ const RefreshControlExample = () => {
   const [refreshing, setRefreshing] = useState(false);
   const onRefresh = useCallback(() => {
     setRefreshing(true);
+    // $FlowFixMe[unused-promise]
     wait(2000).then(() => setRefreshing(false));
   }, []);