feat(client,server): remove tcp feature and code (#2929)

This removes the `tcp` feature from hyper's `Cargo.toml`, and the code it enabled:

- `HttpConnector`
- `GaiResolver`
- `AddrStream`

And parts of `Client` and `Server` that used those types. Alternatives will be available in the `hyper-util` crate.

Closes #2856 
Co-authored-by: MrGunflame <mrgunflame@protonmail.com>

src/client/connect/mod.rs

@@ -55,42 +55,19 @@
 //! # }
 //! ```
 //!
-//! It's worth noting that for `TcpStream`s, the [`HttpConnector`][] is a
-//! better starting place to extend from.
-//!
-//! Using either of the above connector examples, it can be used with the
-//! `Client` like this:
-//!
-//! ```
-//! # #[cfg(feature = "runtime")]
-//! # fn rt () {
-//! # let connector = hyper::client::HttpConnector::new();
-//! // let connector = ...
-//!
-//! let client = hyper::Client::builder()
-//!     .build::<_, hyper::Body>(connector);
-//! # }
-//! ```
-//!
-//!
-//! [`HttpConnector`]: HttpConnector
-//! [`Service`]: crate::service::Service
 //! [`Uri`]: ::http::Uri
 //! [`AsyncRead`]: tokio::io::AsyncRead
 //! [`AsyncWrite`]: tokio::io::AsyncWrite
 //! [`Connection`]: Connection
+//! [`Service`]: crate::service::Service
 use std::fmt;
 
 use ::http::Extensions;
 
-cfg_feature! {
-    #![feature = "tcp"]
+pub use self::http::{HttpConnector, HttpInfo};
 
-    pub use self::http::{HttpConnector, HttpInfo};
-
-    pub mod dns;
-    mod http;
-}
+pub mod dns;
+mod http;
 
 cfg_feature! {
     #![any(feature = "http1", feature = "http2")]