Add TTS API and examples for Dart (#1010)

dart-api-examples/tts/run-coqui.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+
+set -ex
+
+dart pub get
+
+
+# Please visit
+# https://github.com/k2-fsa/sherpa-onnx/releases/tag/tts-models
+# to download more models
+
+if [[ ! -f ./vits-coqui-de-css10/tokens.txt ]]; then
+  curl -SL -O https://github.com/k2-fsa/sherpa-onnx/releases/download/tts-models/vits-coqui-de-css10.tar.bz2
+  tar xvf vits-coqui-de-css10.tar.bz2
+  rm vits-coqui-de-css10.tar.bz2
+fi
+
+# It is a character-based TTS model, so there is no need to use a lexicon
+dart run \
+  ./bin/coqui.dart \
+  --model ./vits-coqui-de-css10/model.onnx \
+  --tokens ./vits-coqui-de-css10/tokens.txt \
+  --sid 0 \
+  --speed 0.7 \
+  --text 'Alles hat ein Ende, nur die Wurst hat zwei.' \
+  --output-wav coqui-0.wav
+
+ls -lh *.wav