wamr-python: Enable debugging WASM and grant dir access (#2449)

- Enable debugging a WASM loaded and executed from Python.
- Expose API to enable access to list of host directories. Similar to --dir in iwasm.
- Add another python language binding sample: native-symbol.

language-bindings/python/wamr-api/samples/native-symbol/compile.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+# Copyright (C) 2019 Intel Corporation.  All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+/opt/wasi-sdk/bin/clang     \
+    -O0 -z stack-size=4096 -Wl,--initial-memory=65536 \
+    -Wl,--export=main -Wl,--export=__main_argc_argv \
+    -Wl,--export=__data_end -Wl,--export=__heap_base \
+    -Wl,--strip-all,--no-entry \
+    -Wl,--allow-undefined \
+    -Wl,--export=c_func\
+    -Wl,--export=add\
+    -o func.wasm func.c