wasi-nn: Enable GPU support (#1922)

- Split logic in several dockers
  - runtime: wasi-nn-cpu and wasi-nn- Nvidia-gpu.
  - compilation: wasi-nn-compile. Prepare the testing wasm and generates the TFLites.
- Implement GPU support for TFLite with Opencl.

core/iwasm/libraries/wasi-nn/test/Dockerfile.base

@@ -0,0 +1,22 @@
+# Copyright (C) 2019 Intel Corporation.  All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+FROM ubuntu:20.04 AS base
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y \
+    cmake build-essential git
+
+WORKDIR /home/wamr
+
+COPY . .
+
+WORKDIR /home/wamr/core/iwasm/libraries/wasi-nn/test/build
+
+RUN cmake \
+  -DWAMR_BUILD_WASI_NN=1 \
+  -DTFLITE_ENABLE_GPU=ON \
+  ..
+
+RUN make -j $(grep -c ^processor /proc/cpuinfo)