MINOR: config: Improve warnings on misplaced rules by adding an optional arg

MINOR: config: Improve warnings on misplaced rules by adding an optional arg

In warnings about misplaced rules, only the first keyword is mentionned. It
works well for http-request or quic-initial rules for instance. But it is a
bit confusing for tcp-request rules, because the layer is missing (session
or content).

To make it a bit systematic (and genric), the second argument can now be
provided. It can be set to NULL if there is no layer or scope. But
otherwise, it may be specified and it will be reported in the warning.

So the following snippet:

    tcp-request content reject if FALSE
    tcp-request session reject if FALSE
    tcp-request connection reject if FALSE

Will now emit the following warnings:

  a 'tcp-request session' rule placed after a 'tcp-request content' rule will still be processed before.
  a 'tcp-request connection' rule placed after a 'tcp-request session' rule will still be processed before.

This patch should fix the issue #2596.