windows js_module_loader_so support

[zeromake]

I've done one before by dlfcn-win32, now use win32 api LoadLibraryW, GetProcAddress, FreeLibrary replace unix dlopen, dlsym, dlclose.

Here's my implementation, ignore xmake build file
zeromake@86b7df5#diff-95fe784bea3e0fbdf30ba834b1a74b538090f4d70f4f8770ef397ef68ec37aa3R482

Run an example

❯ git clone https://github.com/zeromake/quickjs-ng.git
❯ cd quickjs-ng && xmake f -c -y
❯ xmake b qjsc && xmake b qjs && xmake b fib
❯ xmake r qjs ..\..\..\..\examples\test_fib.js
Hello World
fib(10)= 55

But there are still a lot of uncertainties

1. like node native file is .node be supported, but quickjs is .so.
2. fallback path search? Eg: "./fib.so" find ["./fib.so", "./fib-${platform}-${arch}.so"]
3. cmake test windows local native module support

[saghul]

I'd say open a PR and let's go through it!

1. Is of no concern here. On windows shared libraries should have a .dll extension, as is customary.

2. We don't do that for Unix, so not a blocker for Windows.

3. This would be nice yeah, so we are sure it works. There is already a test, it would likely just need some adjustments.

[zeromake]

@saghul ok, I'll bring the PR out first later