Add CXX examples for NeMo TDT ASR. (#2363)

# New Features
- Added new example programs demonstrating streaming speech recognition from a microphone using Parakeet-TDT CTC and Zipformer Transducer models with voice activity detection.
- These examples support microphone input via PortAudio and display recognized text incrementally.

# Bug Fixes
- Improved error handling and logic when opening microphone devices in several example programs for more reliable device initialization.

# Chores
- Updated build configuration to include new executable examples when PortAudio support is enabled.

cxx-api-examples/CMakeLists.txt

@@ -49,6 +49,15 @@ if(SHERPA_ONNX_ENABLE_PORTAUDIO)
     portaudio_static
   )
 
+  add_executable(parakeet-tdt-ctc-simulate-streaming-microphone-cxx-api
+    ./parakeet-tdt-ctc-simulate-streaming-microphone-cxx-api.cc
+    ${CMAKE_CURRENT_LIST_DIR}/../sherpa-onnx/csrc/microphone.cc
+  )
+  target_link_libraries(parakeet-tdt-ctc-simulate-streaming-microphone-cxx-api
+    sherpa-onnx-cxx-api
+    portaudio_static
+  )
+
   add_executable(zipformer-ctc-simulate-streaming-microphone-cxx-api
     ./zipformer-ctc-simulate-streaming-microphone-cxx-api.cc
     ${CMAKE_CURRENT_LIST_DIR}/../sherpa-onnx/csrc/microphone.cc
@@ -57,6 +66,15 @@ if(SHERPA_ONNX_ENABLE_PORTAUDIO)
     sherpa-onnx-cxx-api
     portaudio_static
   )
+
+  add_executable(zipformer-transducer-simulate-streaming-microphone-cxx-api
+    ./zipformer-transducer-simulate-streaming-microphone-cxx-api.cc
+    ${CMAKE_CURRENT_LIST_DIR}/../sherpa-onnx/csrc/microphone.cc
+  )
+  target_link_libraries(zipformer-transducer-simulate-streaming-microphone-cxx-api
+    sherpa-onnx-cxx-api
+    portaudio_static
+  )
 endif()
 
 if(SHERPA_ONNX_HAS_ALSA)