rc.d: add a service jails config to all base system services

This gives more permissions to services (e.g. network access to
services which require this) when they are started as an automatic
service jail.

The sshd patch is important for the sshd-related functionality as
described in the man-page in the service jails part.

The location of the added env vars is supposed to allow overriding them
in rc.conf, and to hard-disable the use of svcj for some parts where it
doesn't make sense or will not work.

Only a subset of all of the services are fully tested (I'm running this
since more than a year with various services started as service jails).
The untested parts should be most of the time ok, in some edge-cases
more permissions are needed inside the service jail.
Differential Revision: https://reviews.freebsd.org/D40371

Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

rc: syscons: Add UEFI special case

Changing cursor, screenmap and setting blanktime doesn't work when booted
with vt(4) and UEFI so add a special case for those depending on machdep.bootmethods.
I have no way to test if this can work with vt(4) and bios boot so just in case
keep calling those for this.

Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D38293

rc.d/syscons: remove spaces before tab

Revert r346017 pending compiled-in zfs fix

PR: 237172
Approved by: jilles
Differential Revision: https://reviews.freebsd.org/D18670

Remove now unnecessary kldstat check before attempting to load modules.

Since r233109, kldload has the -n option, which silently ignores options
that are already loaded.

https://lists.freebsd.org/pipermail/freebsd-rc/2018-December/003899.html

Note that this script no longer reports if the module is already loaded,
but it could be argued this wasn't particularly useful information.

PR: docs/234248
Reviewed by: bcr (docs), kib, rgrimes (visual)
Approved by: jilles
Differential Revision: https://reviews.freebsd.org/D18670

Move the rc framework out of sbin/init into libexec/rc.

The reasons for this are forward looking to pkgbase:
* /sbin/init is a special binary; try not to replace it with
every package update because an rc script was touched.
(a follow-up commit will make init its own package)
* having rc in its own place will allow more easy replacement
of the rc framework with alternatives, such as openrc.

Discussed with: brd (during BSDCam), kmoore
Requested by: cem, bz
PR: 231522
Approved by: re (gjb)