Add tests for libuv component

[KrzysztofCwalina]

No description provided.

[grahamehorner]

I'm happy to pick this up as I'm also doing some Libuv UDP work

however this leads me to a question with regards to what/where the libuv interop/wrapper functionality should be located as it seems that there is duplicated functionality at present in the pipelines & in system.net.libuv ? are these to be consolidated ? as my gut feel is that libuv interop/wrapper shouldn't be inside pipelines as it my be also used by channels ? @KrzysztofCwalina @davidfowl whats your view?

[KrzysztofCwalina]

Ideally, we would have a raw libuv library which would be used by pipelines.

The problem is that it's much more difficult/costly to design a general purpose library like that, than just use libuv as an implementation detaail of pipelines.

But, if you wanted to work on the libuv library, and make it into a nice reusable component, it would be great and I think @davidfowl would like to use it (confirm?)

BTW, the main things I think the library needs:

1. tests
2. make it non allocating, i.e. I am not convinced UVstreams should be classes with inheritance chain. I was hoping to turn them into simple struct handles.
3. We need to make it multithreaded (somehow). There are many ideas for how it could work, none of the great.
4. The APIs support sockets only. They should support other async concepts (like libuv): file i/o, timers, etc.

[ahsonkhan]

We removed Libuv as part of #2244. Closing this issue.