Extend service.enabled() to accept kwargs

This can be used to create stronger checks on the 'enabled' status of a
service. For example, if the service is enabled with the proper flags.
openbsdrcctl: extend enabled() to check flags

On OpenBSD, it's possible to define particular flags a daemon should be
enabled with (ala /etc/sysconfig/... in RedHat). To make sure the flags
are properly updated when changed (in pillars or states), we return a
service as "disabled" if the currently configured flags do not match the
provided ones; this ensures /etc/rc.conf.local is always in sync.
Merge pull request #15509 from ajacoutot/service-enabled-kwargs

Service enabled kwargs