wasi-nn: Apply new architecture (#3692)

ps.
https://github.com/bytecodealliance/wasm-micro-runtime/issues/3677

core/iwasm/libraries/wasi-nn/include/wasi_nn_host.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) 2019 Intel Corporation.  All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#ifndef WASI_NN_HOST_H
+#define WASI_NN_HOST_H
+
+#include "lib_export.h"
+
+uint32_t
+get_wasi_nn_export_apis(NativeSymbol **p_native_symbols);
+
+bool
+wasi_nn_initialize();
+
+void
+wasi_nn_destroy();
+
+#endif /* WASI_NN_HOST_H */

core/iwasm/libraries/wasi-nn/include/wasi_nn_types.h

@@ -126,6 +126,7 @@ typedef enum {
     tensorflowlite,
     ggml,
     autodetect,
+    unknown_backend,
 } graph_encoding;
 
 // Define where the graph should be executed.
@@ -161,9 +162,6 @@ typedef struct {
     BACKEND_DEINITIALIZE deinit;
 } api_function;
 
-bool
-wasi_nn_register_backend(api_function apis);
-
 void
 wasi_nn_dump_tensor_dimension(tensor_dimensions *dim, int32_t output_len,
                               char *output);