Allow to track service violations in conn.log.

This introduces ian options, DPD::track_removed_services_in_connection.
It adds failed services to the services column, prefixed with a
"-".

Alternatively, this commit also adds
policy/protocols/conn/failed-services.zeek, which provides the same
information in a new column in conn.log.

testing/btest/scripts/base/frameworks/analyzer/dpd-logging-configuration.zeek

@@ -0,0 +1,7 @@
+# @TEST-DOC: Check if DPD options on violations work.
+# @TEST-EXEC: zeek -r $TRACES/ftp/ftp-invalid-reply-code.pcap %INPUT
+# @TEST-EXEC: btest-diff conn.log
+
+@load policy/protocols/conn/failed-services
+
+redef DPD::track_removed_services_in_connection = T;