Wrap offline ASR APIs to dart (#961)

sherpa-onnx/flutter/example/lib/non_streaming_paraformer_asr_test.dart

@@ -0,0 +1,47 @@
+// Copyright (c)  2024  Xiaomi Corporation
+import 'package:path/path.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:flutter/services.dart' show rootBundle;
+import 'dart:typed_data';
+import "dart:io";
+
+import 'package:sherpa_onnx/sherpa_onnx.dart' as sherpa_onnx;
+import './utils.dart';
+
+Future<void> testNonStreamingParaformerAsr() async {
+  var model = 'assets/sherpa-onnx-paraformer-zh-2023-03-28/model.int8.onnx';
+  var tokens = 'assets/sherpa-onnx-paraformer-zh-2023-03-28/tokens.txt';
+  var testWave = 'assets/sherpa-onnx-paraformer-zh-2023-03-28/test_wavs/0.wav';
+
+  model = await copyAssetFile(src: model, dst: 'model.int8.onnx');
+  tokens = await copyAssetFile(src: tokens, dst: 'tokens.txt');
+  testWave = await copyAssetFile(src: testWave, dst: '0.wav');
+
+  final paraformer = sherpa_onnx.OfflineParaformerModelConfig(
+    model: model,
+  );
+
+  final modelConfig = sherpa_onnx.OfflineModelConfig(
+    paraformer: paraformer,
+    tokens: tokens,
+    modelType: 'paraformer',
+  );
+
+  final config = sherpa_onnx.OfflineRecognizerConfig(model: modelConfig);
+  print(config);
+  final recognizer = sherpa_onnx.OfflineRecognizer(config);
+
+  final waveData = sherpa_onnx.readWave(testWave);
+  final stream = recognizer.createStream();
+
+  stream.acceptWaveform(
+      samples: waveData.samples, sampleRate: waveData.sampleRate);
+  recognizer.decode(stream);
+
+  final result = recognizer.getResult(stream);
+  print('result is: ${result}');
+
+  print('recognizer: ${recognizer.ptr}');
+  stream.free();
+  recognizer.free();
+}