(asys) Add libuv wrappers

[Aurel300]

See HaxeFoundation/haxe#8817

Some TODOs marked in code. Additional things to investigate:

• use GC finalisers rather than noptr? (e.g. close file when handle is no longer reachable from Haxe code)

CI TODO:

• build 32-bit libuv on Linux32
• install libuv on Windows

[ConstNW]

@Aurel300, do you have any progress on this? can i take a look?

[sonygod]

any fixed here ? @Aurel300 ?

I like your udp function in libuv.

[Aurel300]

@ConstNW @sonygod This is temporarily on hold. First we need to finalise the actual asys APIs (HaxeFoundation/haxe#8832) – we have agreed that some changes need to be made (e.g. dropping the streams, replacing the socket data signals with callback-based methods for simplicity and consistency). I believe @RealyUniqueName is currently working on that. Once the APIs are decided, individual targets can be implemented.

[piboistudios]

@Aurel300 Wow, I've been researching async IO and brainstorming solutions to implementing it in Haxe (particularly HL) and I've repeatedly stumbled across your name.

Glad to see you are diligently working at this task, I wish I could be of help, but I haven't compiled C in over 2 years, all I can say is I'm sure the entire Haxe community looks forward to your success! This is the most exciting proposal I've read about in a while.