Add Dart API for Kokoro TTS models (#1723)

dart-api-examples/tts/run-kokoro-en.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -ex
+
+dart pub get
+
+# please visit
+# https://k2-fsa.github.io/sherpa/onnx/tts/pretrained_models/kokoro.html
+# to download more models
+if [ ! -f ./kokoro-en-v0_19/model.onnx ]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/kokoro-en-v0_19.tar.bz2
+  tar xf kokoro-en-v0_19.tar.bz2
+  rm kokoro-en-v0_19.tar.bz2
+fi
+
+dart run \
+  ./bin/kokoro-en.dart \
+  --model ./kokoro-en-v0_19/model.onnx \
+  --voices ./kokoro-en-v0_19/voices.bin \
+  --tokens ./kokoro-en-v0_19/tokens.txt \
+  --data-dir ./kokoro-en-v0_19/espeak-ng-data \
+  --sid 9 \
+  --speed 1.0 \
+  --output-wav kokoro-en-9.wav \
+  --text "Friends fell out often because life was changing so fast. The easiest thing in the world was to lose touch with someone." \
+
+ls -lh *.wav