Implement Future for RequestBuilder

[NeoLegends]

Hey, WDYT about implementing Future for RequestBuilder directly?

The future would, when awaited, consume the RequestBuilder and send the request, just what .send() would do. This would shorten common patterns like client.get("http://example.com").send().await to client.get("http://example.com").await. Even though .send() is only 7 characters, it kind of bothers me to have to type it every time, when an .await would already suffice.

[NeoLegends]

If you think this is a good idea, I'd be happy to send in a PR for the implementation. :)

[seanmonstar]

I have wanted something like this, but I don't think having the builders implement Future directly is the best option. I tried adding IntoFuture to the standard library, it's stalled due to compiler regressions:

rust-lang/rust#67982

[NeoLegends]

I see, IntoFuture really is the way to go here. Keep this issue open to track that?

[dbofmmbt]

I guess this issue could be closed in favor of #1632, based on the previous discussion.