MASM (Microsoft Macro Assembler) needs to be enabled to successfully
compile .asm files on Windows. Without enabling this language
automatically in runtime_lib.cmake, Windows cmake projects using WAMR
get hard-to-diagnose linker errors about missing symbols as the assembly
file is not compiled at all.
Introduce module instance context APIs which can set one or more contexts created
by the embedder for a wasm module instance:
```C
wasm_runtime_create_context_key
wasm_runtime_destroy_context_key
wasm_runtime_set_context
wasm_runtime_set_context_spread
wasm_runtime_get_context
```
And make libc-wasi use it and set wasi context as the first context bound to the wasm
module instance.
Also add samples.
Refer to https://github.com/bytecodealliance/wasm-micro-runtime/issues/2460.