fw4: add support for zone log_limit
It is equivalent to the fw3 feature, affecting not accepted packets
and rules explicitily setting the log property.
Input rules not associated with a zone will not have log_limit.
Forward rules will use src zone log_limit or, if missing, dest zone
log_limit.
Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
[properly handle null zone references, whitespace and indentation cleanup,
testcase cleanup, slight code simplification, use dot for named limit,
properly format limit expressions]
Signed-off-by: Jo-Philipp Wich <jo@mein.io>