Add Android demo for audio tagging (#776)

See https://k2-fsa.github.io/sherpa/onnx/audio-tagging/apk.html

kotlin-api-examples/OfflineStream.kt

@@ -1,24 +0,0 @@
-package com.k2fsa.sherpa.onnx
-
-class OfflineStream(var ptr: Long) {
-    fun acceptWaveform(samples: FloatArray, sampleRate: Int) =
-        acceptWaveform(ptr, samples, sampleRate)
-
-    protected fun finalize() {
-      if(ptr != 0L) {
-        delete(ptr)
-        ptr = 0
-      }
-    }
-
-    fun release() = finalize()
-
-    private external fun acceptWaveform(ptr: Long, samples: FloatArray, sampleRate: Int)
-    private external fun delete(ptr: Long)
-
-    companion object {
-        init {
-            System.loadLibrary("sherpa-onnx-jni")
-        }
-    }
-}

kotlin-api-examples/OfflineStream.kt

@@ -0,0 +1 @@
+../android/SherpaOnnxAudioTagging/app/src/main/java/com/k2fsa/sherpa/onnx/audio/tagging/OfflineStream.kt