Refactor kokoro export (#2302)

- generate samples for https://k2-fsa.github.io/sherpa/onnx/tts/all/
- provide int8 model for kokoro v0.19 kokoro-int8-en-v0_19.tar.bz2

scripts/kokoro/v0.19/generate_samples.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+# Copyright    2025  Xiaomi Corp.        (authors: Fangjun Kuang)
+"""
+Generate samples for
+https://k2-fsa.github.io/sherpa/onnx/tts/all/
+"""
+
+import sherpa_onnx
+import soundfile as sf
+
+from generate_voices_bin import speaker2id
+
+config = sherpa_onnx.OfflineTtsConfig(
+    model=sherpa_onnx.OfflineTtsModelConfig(
+        kokoro=sherpa_onnx.OfflineTtsKokoroModelConfig(
+            model="./model.onnx",
+            voices="./voices.bin",
+            tokens="./tokens.txt",
+            data_dir="./espeak-ng-data",
+        ),
+        num_threads=2,
+    ),
+    max_num_sentences=1,
+)
+
+if not config.validate():
+    raise ValueError("Please check your config")
+
+tts = sherpa_onnx.OfflineTts(config)
+text = "Friends fell out often because life was changing so fast. The easiest thing in the world was to lose touch with someone."
+
+for s, i in speaker2id.items():
+    print(s, i, len(speaker2id))
+    audio = tts.generate(text, sid=i, speed=1.0)
+
+    sf.write(
+        f"./hf/kokoro/v0.19/mp3/{i}-{s}.mp3",
+        audio.samples,
+        samplerate=audio.sample_rate,
+    )