Upgrade to hyper/http 1.0

[jonhoo]

Now that version 1.0 of the hyper and http* crates are out, octocrab should probably follow suit. Unfortunately, it's a decently heavy lift, especially due to Body changing from a concrete type to a trait (hyperium/hyper#2345). I took a stab at it, but quickly got lost in a sea of <B: Body>s, and figured I'd leave it to those who know the library best.

A few bits I did pick up that may come in handy for someone wanting to take this on:

• body::to_bytes(body).await? becomes body.collect().await?.to_bytes() via http_body_util::BodyExt
• The old Body becomes BoxBody<hyper::body::Bytes, hyper::Error> via http_body_util::combinators::BoxBody if you want to keep it fully type-erased like it is today.
• There is no more pooling http client, nor a Connector trait (or rather, they're relegated to hyper_util::client::legacy). Instead, there is now hyper::client::conn::http1::Connection.

Also note that this will obviate:

• Update tower-http requirement from 0.4.0 to 0.5.0 #491
• Update http requirement from 0.2.5 to 1.0.0 #489
• Update hyper requirement from 0.14.13 to 1.0.0 #488
• Update http-body requirement from 0.4.5 to 1.0.0 #487

which can probably all be closed in favor of this tracking issue.

[XAMPPRocky]

Thank you for your issue!

I took a stab at it, but quickly got lost in a sea of <B: Body>s

Yeah I tried upgrading other crates I maintain to 1.0.0 as a test, but this upgrade has been pretty painful in my experience, so I haven't made it a priority. I am able to help review the changes. I wonder if it's worth while to make a separate branch from it, so that we can continously make PRs for it, rather than require that someone migrate everything.

[jonhoo]

Also worth linking this, which it took me a bit to find: https://hyper.rs/guides/1/upgrading/