`futures_core::Stream` interop

[teohhanhui]

While it's not in std, it's most definitely a de facto standard at this point...

Perhaps related: #17

[pchickey]

How does #80 look? What other impls should there be? Could you help contribute some tests to that PR?

[teohhanhui]

I'm not sure why I didn't specify this in the OP, but specifically I was looking at wstd::http::Client and couldn't find a way to send a request with a futures_core::Stream body? (reqwest seems to support that.)

So if I'm not mistaken, a way to go from a futures_core::Stream to a wstd::http::body::OutgoingBody?