fix(llc): Fix attachment upload state uneven progress. (#315)

* feat(llc): Add rate limiter functions.
fix(llc): Fix attachment upload state uneven progress.

Signed-off-by: Sahil Kumar <[email protected]>

* feat(llc): Export `async.dart` and `rate_limit.dart`

Signed-off-by: Sahil Kumar <[email protected]>

* refactor(llc): Replace our `rate_limit` implementation with the dart port of js `lodash` to better handlw `cancel` and `flush` functions.

Signed-off-by: Sahil Kumar <[email protected]>

* fix(UI-Kit): Make android example run on real devices

Signed-off-by: Sahil Kumar <[email protected]>

* fix offline behaviour

Co-authored-by: Salvatore Giordano <[email protected]>

packages/stream_chat/lib/stream_chat.dart

@@ -1,5 +1,6 @@
 library stream_chat;
 
+export 'package:async/async.dart';
 export 'package:dio/src/dio_error.dart';
 export 'package:dio/src/multipart_file.dart';
 export 'package:dio/src/options.dart' show ProgressCallback;
@@ -14,6 +15,7 @@ export './src/attachment_file_uploader.dart' show AttachmentFileUploader;
 export './src/client.dart';
 export './src/db/chat_persistence_client.dart';
 export './src/event_type.dart';
+export './src/extensions/rate_limit.dart';
 export './src/extensions/string_extension.dart';
 export './src/models/action.dart';
 export './src/models/attachment.dart';