Fix terminate not being called on connection close in HTTP/1.1

Introduces the new stream_handler_SUITE test suite. More cases
will be added later on.

test/handlers/stream_handler_h.erl

@@ -0,0 +1,34 @@
+%% This module behaves differently depending on a specific header.
+
+-module(stream_handler_h).
+-behavior(cowboy_stream).
+
+-export([init/3]).
+-export([data/4]).
+-export([info/3]).
+-export([terminate/3]).
+-export([early_error/5]).
+
+init(StreamID, Req, Opts) ->
+	%% @todo Vary behavior depending on x-test-case.
+	Pid = list_to_pid(binary_to_list(cowboy_req:header(<<"x-test-pid">>, Req))),
+	Pid ! {Pid, self(), init, StreamID, Req, Opts},
+	{[{headers, 200, #{}}], Pid}.
+
+data(StreamID, IsFin, Data, State=Pid) ->
+	Pid ! {Pid, self(), data, StreamID, IsFin, Data, State},
+	{[], State}.
+
+info(StreamID, Info, State=Pid) ->
+	Pid ! {Pid, self(), info, StreamID, Info, State},
+	{[], State}.
+
+terminate(StreamID, Reason, State=Pid) ->
+	Pid ! {Pid, self(), terminate, StreamID, Reason, State},
+	ok.
+
+%% This clause can only test for early errors that reached the required header.
+early_error(StreamID, Reason, PartialReq, Resp, Opts) ->
+	Pid = list_to_pid(binary_to_list(cowboy_req:header(<<"x-test-pid">>, PartialReq))),
+	Pid ! {Pid, self(), early_error, StreamID, Reason, PartialReq, Resp, Opts},
+	Resp.