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

sherpa-onnx/csrc/offline-tts.h

@@ -9,6 +9,11 @@
 #include <string>
 #include <vector>
 
+#if __ANDROID_API__ >= 9
+#include "android/asset_manager.h"
+#include "android/asset_manager_jni.h"
+#endif
+
 #include "sherpa-onnx/csrc/offline-tts-model-config.h"
 #include "sherpa-onnx/csrc/parse-options.h"
 
@@ -38,6 +43,11 @@ class OfflineTts {
  public:
   ~OfflineTts();
   explicit OfflineTts(const OfflineTtsConfig &config);
+
+#if __ANDROID_API__ >= 9
+  OfflineTts(AAssetManager *mgr, const OfflineTtsConfig &config);
+#endif
+
   // @param text A string containing words separated by spaces
   // @param sid Speaker ID. Used only for multi-speaker models, e.g., models
   //            trained using the VCTK dataset. It is not used for