Support streaming zipformer CTC (#496)

* Support streaming zipformer CTC

* test online zipformer2 CTC

* Update doc of sherpa-onnx.cc

* Add Python APIs for streaming zipformer2 ctc

* Add Python API examples for streaming zipformer2 ctc

* Swift API for streaming zipformer2 CTC

* NodeJS API for streaming zipformer2 CTC

* Kotlin API for streaming zipformer2 CTC

* Golang API for streaming zipformer2 CTC

* C# API for streaming zipformer2 CTC

* Release v1.9.6

sherpa-onnx/csrc/online-zipformer2-ctc-model-config.cc

@@ -0,0 +1,41 @@
+// sherpa-onnx/csrc/online-zipformer2-ctc-model-config.cc
+//
+// Copyright (c)  2023  Xiaomi Corporation
+
+#include "sherpa-onnx/csrc/online-zipformer2-ctc-model-config.h"
+
+#include "sherpa-onnx/csrc/file-utils.h"
+#include "sherpa-onnx/csrc/macros.h"
+
+namespace sherpa_onnx {
+
+void OnlineZipformer2CtcModelConfig::Register(ParseOptions *po) {
+  po->Register("zipformer2-ctc-model", &model,
+               "Path to CTC model.onnx. See also "
+               "https://github.com/k2-fsa/icefall/pull/1413");
+}
+
+bool OnlineZipformer2CtcModelConfig::Validate() const {
+  if (model.empty()) {
+    SHERPA_ONNX_LOGE("--zipformer2-ctc-model is empty!");
+    return false;
+  }
+
+  if (!FileExists(model)) {
+    SHERPA_ONNX_LOGE("--zipformer2-ctc-model %s does not exist", model.c_str());
+    return false;
+  }
+
+  return true;
+}
+
+std::string OnlineZipformer2CtcModelConfig::ToString() const {
+  std::ostringstream os;
+
+  os << "OnlineZipformer2CtcModelConfig(";
+  os << "model=\"" << model << "\")";
+
+  return os.str();
+}
+
+}  // namespace sherpa_onnx