wasi-nn: make the host use the wasi_ephemeral_nn version of tensor_data (#4411)

the motivations:

* make the actual input size available to the backends.
  (currently the backends have to make a guess from shape/type.)

* make the host logic look a bit similar to wasi_ephemeral_nn.

this is a backend api/abi change.

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

@@ -99,7 +99,7 @@ typedef enum {
 // 4-byte f32 elements would have a data array of length 16). Naturally, this
 // representation requires some knowledge of how to lay out data in
 // memory--e.g., using row-major ordering--and could perhaps be improved.
-#if WASM_ENABLE_WASI_EPHEMERAL_NN != 0 && defined(__wasm__)
+#if !defined(__wasm__) || WASM_ENABLE_WASI_EPHEMERAL_NN != 0
 typedef struct {
     uint8_t *buf;
     uint32_t size;