Remove $FreeBSD$: two-line nroff pattern

Remove /^\.\\"\n\.\\"\s*\$FreeBSD\$$\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

cli.lua.8: make the command match the code

It's disable-device, not device-disable

Spotted by: jrtc27
Sponsored by: Netflix

lua loader: Add disable-device to disable a device.

disable-device fooX will set hint.foo.X.disabled=1 as a way to easily
disable a device attaching during boot.

Reviewed by: tsoome
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D31297

lualoader: cli: provide a show-module-options loader command

This effectively dumps everything lualoader knows about to the console using
the libsa pager; that particular lua interface was added in r368591.

A pager stub implementation has been added that just dumps the output as-is
as a compat shim for older loader binaries that do not have lpager. This
stub should be moved into a more appropriate .lua file if we add anything
else that needs the pager.

lualoader: provide module-manipulation commands

Specifically, we have:
- enable-module
- disable-module
- toggle-module

These can be used to add/remove modules to be loaded or force modules to be
loaded in spite of modules_blacklist. In the typical case, a user is
expected to use them to recover an issue happening due to a module directive
they've added to their loader.conf or because they discover that they've
under-specified what to load.

MFC after: 1 week

lualoader: Add reload-conf loader command

This command will trigger a reload of the configuration from disk. This is
useful if you've changed currdev from recovery media to local disk as much
as I have over the past ~2 hours and are tired of the extra keystrokes.

This is really just a glorified shortcut, but reload-conf is likely easier
to remember for other people and does save some keystrokes when reloading
the configuration. It is also resilient to the underlying config method
changing interface, but this is unlikely to happen.

MFC after: 1 week

lualoader: Implement boot-conf

MFC after: 3 days

lualoader: Add cli.lua(8) to the tree

Reviewed by: rpokala
Differential Revision: https://reviews.freebsd.org/D14818