Move plugins to external folder

applications/external/wav_player/wav_player_hal.h

@@ -0,0 +1,23 @@
+#pragma once
+#include <stdint.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void wav_player_speaker_init();
+
+void wav_player_speaker_start();
+
+void wav_player_speaker_stop();
+
+void wav_player_dma_init(uint32_t address, size_t size);
+
+void wav_player_dma_start();
+
+void wav_player_dma_stop();
+
+#ifdef __cplusplus
+}
+#endif