(legacy) cleanup system_advanced_network.php and add switch for vlanhwfilter disable ( https://github.com/opnsense/core/issues/252 )

/var/run was cleared out before, but we'd rather not keep it
this way...  It is for pid files, nothing else.  Move the
terrible firmware dirty markers to /tmp instead.  Eventually,
we need a better way to keep track of subsystem state.  Cluttering
multiple files all over the disk is not a good solution.

(legacy) remove utils.inc, move shared functions into services.inc and single used functions into respective location.

While there, move the IPv4 sibling and add a require for the remaining
outside caller.