Support IPv6 URIs with rustls

[mjquigley]

When trying to connect to an IPv6 address with the rustls feature enabled, the connection fails because rustls parses the domain as an std::net::IPAddr which expects the IP to not have the square brackets around it e.g. 2001:db8:3333:4444:CCCC:DDDD:EEEE:FFFF instead of [2001:db8:3333:4444:CCCC:DDDD:EEEE:FFFF]. But when providing/parsing an http::URI the square brackets are required.

If we strip the square brackets from the host before passing it to rustls the connection works.

Repro snippet:

tokio_tungstenite::connect_async("wss://[2001:db8:3333:4444:CCCC:DDDD:EEEE:FFFF]:443").await.expect("to connect");

[agalakhov]

This looks good, but please rename the commit so that one can understand what's changed.