Detect misconfigured HTTP clients

It also happens from time to time that HTTP clients use the wrong port
5672. Like for TLS clients connecting to 5672, RabbitMQ now prints a
more descriptive log message.

For example
```
curl http://localhost:5672
```
will log
```
[info] <0.946.0> accepting AMQP connection [::1]:57736 -> [::1]:5672
[error] <0.946.0> closing AMQP connection <0.946.0> ([::1]:57736 -> [::1]:5672, duration: '1ms'):
[error] <0.946.0> {detected_unexpected_http_header,<<"GET / HT">>}
```

We only check here for GET and not for all other HTTP methods, since
that's the most common case.

Author: ansd

deps/rabbit/src/rabbit_reader.erl

@@ -1140,6 +1140,9 @@ handle_input(handshake, <<Other:8/binary, _/binary>>, #v1{sock = Sock}) ->
                  <<16#16, 16#03, _Ver2, _Len1, _Len2, 16#01, _, _>> ->
                      %% Looks like a TLS client hello.
                      detected_unexpected_tls_header;
+                 <<"GET ", _URL/binary>> ->
+                     %% Looks like an HTTP request.
+                     detected_unexpected_http_header;
                  _ ->
                      bad_header
              end,