[LLC, UI-KIT] Add support for custom attachment upload delegate

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

packages/stream_chat/lib/src/api/channel.dart

@@ -223,19 +223,27 @@ class Channel {
   }
 
   /// Send a file to this channel
-  Future<SendFileResponse> sendFile(MultipartFile file) async {
+  Future<SendFileResponse> sendFile(
+    MultipartFile file, {
+    ProgressCallback onSendProgress,
+  }) async {
     final response = await _client.post(
       '$_channelURL/file',
       data: FormData.fromMap({'file': file}),
+      onSendProgress: onSendProgress,
     );
     return _client.decode(response.data, SendFileResponse.fromJson);
   }
 
   /// Send an image to this channel
-  Future<SendImageResponse> sendImage(MultipartFile file) async {
+  Future<SendImageResponse> sendImage(
+    MultipartFile file, {
+    ProgressCallback onSendProgress,
+  }) async {
     final response = await _client.post(
       '$_channelURL/image',
       data: FormData.fromMap({'file': file}),
+      onSendProgress: onSendProgress,
     );
     return _client.decode(response.data, SendImageResponse.fromJson);
   }

packages/stream_chat/lib/src/client.dart

@@ -794,9 +794,14 @@ class StreamChatClient {
   Future<Response<String>> post(
     String path, {
     dynamic data,
+    ProgressCallback onSendProgress,
   }) async {
     try {
-      final response = await httpClient.post<String>(path, data: data);
+      final response = await httpClient.post<String>(
+        path,
+        data: data,
+        onSendProgress: onSendProgress,
+      );
       return response;
     } on DioError catch (error) {
       throw _parseError(error);

packages/stream_chat/lib/stream_chat.dart

@@ -2,6 +2,7 @@ library stream_chat;
 
 export 'package:dio/src/dio_error.dart';
 export 'package:dio/src/multipart_file.dart';
+export 'package:dio/src/options.dart' show ProgressCallback;
 export 'package:logging/logging.dart' show Logger, Level;
 
 export './src/api/channel.dart';