Add jni interface and kotlin API examples for TTS. (#381)

sherpa-onnx/csrc/offline-tts-impl.h

@@ -8,6 +8,11 @@
 #include <memory>
 #include <string>
 
+#if __ANDROID_API__ >= 9
+#include "android/asset_manager.h"
+#include "android/asset_manager_jni.h"
+#endif
+
 #include "sherpa-onnx/csrc/offline-tts.h"
 
 namespace sherpa_onnx {
@@ -18,6 +23,11 @@ class OfflineTtsImpl {
 
   static std::unique_ptr<OfflineTtsImpl> Create(const OfflineTtsConfig &config);
 
+#if __ANDROID_API__ >= 9
+  static std::unique_ptr<OfflineTtsImpl> Create(AAssetManager *mgr,
+                                                const OfflineTtsConfig &config);
+#endif
+
   virtual GeneratedAudio Generate(const std::string &text, int64_t sid = 0,
                                   float speed = 1.0) const = 0;
 };