MFC r314592: Fix JSON output.

MFC r311804: Rewrite CTL statistics in more simple and scalable way.

Instead of collecting statistics for each combination of ports and logical
units, that consumed ~45KB per LU with present number of ports, collect
separate statistics for every port and every logical unit separately, that
consume only 176 bytes per each single LU/port. This reduces struct
ctl_lun size down to just 6KB.

Also new IOCTL API/ABI does not hardcode number of LUs/ports, and should
allow handling of very large quantities.

Old API is still enabled in stable branches for compatibility reasons.

MFC r288059: Bunch of improvements to ctlstat.

Add -p option to allow filtering by ports.
Make -l and -p options work in all modes as filters.
Improve output formatting to better fit columns.

MFC r288043:
Output times as normal microseconds, rather then in bintime format.

MFC r286806: Drop "internal" CTL frontend.

Its idea was to be a simple initiator and execute several commands from
kernel level, but FreeBSD never had consumer for that functionality,
while its implementation polluted many unrelated places.

MFC r278362: Fix couple issues in ctlstat header printing.

MFC r288059: Bunch of improvements to ctlstat.

Add -p option to allow filtering by ports.
Make -l and -p options work in all modes as filters.
Improve output formatting to better fit columns.

MFC r288043:
Output times as normal microseconds, rather then in bintime format.

MFC r286806: Drop "internal" CTL frontend.

Its idea was to be a simple initiator and execute several commands from
kernel level, but FreeBSD never had consumer for that functionality,
while its implementation polluted many unrelated places.

MFC r278362: Fix couple issues in ctlstat header printing.