a7a14b78c1
Add `DOM.AsyncIterable` to the shared TypeScript configuration in `@backstage/cli`, making standard async iteration methods available on DOM APIs like `FileSystemDirectoryHandle`. This aligns behavior with TypeScript 6.0, where this lib is included in `DOM` by default. With the async iterable types now available, replace the custom `IterableDirectoryHandle` and `WritableFileHandle` types in the scaffolder plugin with the standard `FileSystemDirectoryHandle` and `FileSystemFileHandle` DOM types. Add type guard functions for `FileSystemHandle` since it is not a discriminated union. Signed-off-by: Jon Koops <jonkoops@gmail.com>