Allow setting socket parameters

[bugadani]

At least timeout and keep_alive would be good to configure

[ShaunSHamilton]

At least as far as the socket timeout goes, this is controlled by the TCP client (impl TcpConnect) passed to the HttpClient. So, I cannot see a reason for this library to take a mutable ref of the client in order to offer this configuration.

In my case, setting a timeout looked like:

        // ...
        let mut tcp_client = embassy_net::tcp::client::TcpClient::new(stack, &client_state);
        tcp_client.set_timeout(Some(Duration::from_millis(3000)));

        let dns_client = embassy_net::dns::DnsSocket::new(stack);
        let tls_config = reqwless::client::TlsConfig::new(seed, &mut tls_read_buffer, &mut tls_write_buffer, TlsVerify::None);

        let mut http_client = reqwless::client::HttpClient::new_with_tls(&tcp_client, &dns_client, tls_config);