WebSocket: Introduce new analyzer and log

This adds a new WebSocket analyzer that is enabled with the HTTP upgrade
mechanism introduced previously. It is a first implementation in BinPac with
manual chunking of frame payload. Configuration of the analyzer is sketched
via the new websocket_handshake() event and a configuration BiF called
WebSocket::__configure_analyzer(). In short, script land collects WebSocket
related HTTP headers and can forward these to the analyzer to change its
parsing behavior at websocket_handshake() time. For now, however, there's
no actual logic that would change behavior based on agreed upon extensions
exchanged via HTTP headers (e.g. frame compression). WebSocket::Configure()
simply attaches a PIA_TCP analyzer to the WebSocket analyzer for dynamic
protocol detection (or a custom analyzer if set). The added pcaps show this
in action for tunneled ssh, http and https using wstunnel. One test pcap is
Broker's WebSocket traffic from our own test suite, the other is the
Jupyter websocket traffic from the ticket/discussion.

This commit further adds a basic websocket.log that aggregates the WebSocket
specific headers (Sec-WebSocket-*) headers into a single log.

Closes #3424

testing/btest/scripts/base/protocols/websocket/wstunnel-http.zeek

@@ -0,0 +1,16 @@
+# @TEST-DOC: Test HTTP connection tunneled within WebSocket using wstunnel. Seems something in the HTTP scripts gets confused :-/
+#
+# @TEST-EXEC: zeek -b -r $TRACES/websocket/wstunnel-http.pcap %INPUT
+#
+# @TEST-EXEC: zeek-cut -m ts uid history service < conn.log > conn.log.cut
+# @TEST-EXEC: zeek-cut -m ts uid host uri status_code user_agent < http.log > http.log.cut
+
+# @TEST-EXEC: btest-diff conn.log.cut
+# @TEST-EXEC: btest-diff http.log.cut
+# @TEST-EXEC: btest-diff websocket.log
+# @TEST-EXEC: test ! -f analyzer.log
+# @TEST-EXEC: test ! -f weird.log
+
+@load base/protocols/conn
+@load base/protocols/ssh
+@load base/protocols/websocket