TF-2667 Add cancel button in progress send message dialog

lib/main/exceptions/remote_exception.dart

@@ -11,7 +11,7 @@ abstract class RemoteException with EquatableMixin implements Exception {
   static const badCredentials = 'Bad credentials';
   static const socketException = 'Socket exception';
 
-  final String? message;
+  final Object? message;
   final int? code;
 
   const RemoteException({this.code, this.message});
@@ -25,7 +25,7 @@ class BadCredentialsException extends RemoteException {
 }
 
 class UnknownError extends RemoteException {
-  const UnknownError({int? code, String? message}) : super(code: code, message: message);
+  const UnknownError({int? code, Object? message}) : super(code: code, message: message);
 
   @override
   List<Object?> get props => [code, message];

lib/main/exceptions/remote_exception_thrower.dart

@@ -53,7 +53,7 @@ class RemoteExceptionThrower extends ExceptionThrower {
             if (error.error is SocketException) {
               throw const SocketError();
             } else if (error.error != null) {
-              throw UnknownError(message: error.error!.toString());
+              throw UnknownError(message: error.error);
             } else {
               throw const UnknownError();
             }

lib/main/localizations/app_localizations.dart

@@ -4016,4 +4016,11 @@ class AppLocalizations {
       'Saving of the message to drafts folder failed.\nAn error occurred while saving mail.',
       name: 'warningMessageWhenSaveEmailToDraftsFailure');
   }
+
+  String get canceling {
+    return Intl.message(
+      'Canceling',
+      name: 'canceling'
+    );
+  }
 }