Add pre-packaged dependency libraries (ESP32-audioI2S and PNGdec)

libraries/ESP32-audioI2S/examples/I2Saudio_SD_MMC/I2Saudio_SD_MMC.cpp

@@ -0,0 +1,38 @@
+#include "Arduino.h"
+#include "Audio.h"
+#include "SD_MMC.h"
+
+#define I2S_DOUT            9
+#define I2S_BCLK            3
+#define I2S_LRC             1
+#define SD_MMC_D0          11
+#define SD_MMC_CLK         13
+#define SD_MMC_CMD         14
+
+Audio audio;
+
+void my_audio_info(Audio::msg_t m) {
+    Serial.printf("%s: %s\n", m.s, m.msg);
+}
+
+void setup() {
+    Audio::audio_info_callback = my_audio_info;
+    Serial.begin(115200);
+    pinMode(SD_MMC_D0, INPUT_PULLUP);
+    SD_MMC.setPins(SD_MMC_CLK, SD_MMC_CMD, SD_MMC_D0);
+    SD_MMC.begin("/sdcard", true);
+
+    audio.setPinout(I2S_BCLK, I2S_LRC, I2S_DOUT);
+    audio.setVolume(12); // default 0...21
+    audio.connecttoFS(SD_MMC, "/test.wav");
+}
+
+void loop() {
+    audio.loop();
+    vTaskDelay(1);
+}
+
+// optional
+void audio_info(const char *info){
+    Serial.print("info        "); Serial.println(info);
+}