Add VAD + Non-streaming ASR example for JavaScript API.

[csukuangfj]

It also fixes the following error

undefined:1
{"text": " But whenever I complain, my mother would just give me one of those looks and she'd say, "This is no picnic for me, either, Buster."", "tim
estamps": [], "tokens":[" But", " whenever", " I", " complain", ",", " my", " mother", " would", " just", " give", " me", " one", " of", " those", "
looks", " and", " she", "'d", " say", ",", " "", "This", " is", " no", " picnic", " for", " me", ",", " either", ",", " Buster", ".""], "words": []}
                                                                                                    ^

SyntaxError: Expected ',' or '}' after property value in JSON at position 100 (line 1 column 101)
    at JSON.parse (<anonymous>)
    at OfflineRecognizer.getResult (/Users/fangjun/open-source/sherpa-onnx/nodejs-addon-examples/node_modules/sherpa-onnx-node/non-streaming-asr.js:3
4:17)
    at Object.<anonymous> (/Users/fangjun/open-source/sherpa-onnx/nodejs-addon-examples/test_vad_with_non_streaming_asr_whisper.js:88:26)
    at Module._compile (node:internal/modules/cjs/loader:1376:14)

When text or tokens contains " (double quotes), we need to skip it when converting to a json string.