devmatch(8): Grammar fix

Event: Advanced UNIX Programming Course (Fall'23) at NTHU.
Pull Request: https://github.com/freebsd/freebsd-src/pull/1034

Remove $FreeBSD$: two-line nroff pattern

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

devmatch: introduce quiet command line option

In setups without hints whatsoever one can get a long list of
"Can't read linker hints file" error messages during boot.
Add a -q/--quiet option which would suppress the noise and leave
space for more essential information.

While here switch to a pre-defined exit code from sysexits.

MFC after: 4 weeks
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D41443

Make SYNOPSIS match DESCRIPTION.

While there, fix nits reported by igor and mandoc -T lint.

Differential Revision: https://reviews.freebsd.org/D35405

Reviewed by: debdrup, gbe, gjb

Approved by: gjb (mentor)

MFC after: 3 days

devmatch: Allow devmatch_blocklist to be set in kenv too

Add in all the variables set in the kenv variable devmatch_blocklist
too. This allows blocking autoloading from the boot loader.

Sponsored by: Netflix
Reviewed by: 0mp
Differential Revision: https://reviews.freebsd.org/D32171

devmatch(8): Fix section ordering

- sections out of conventional order: Sh HISTORY

devmatch: First appeared in 12.0

Document that devmatch first appeared in FreeBSD 12.0. Also can't -> can not. But
it doesn't help the sentence much.

MFC After: 3 days

Fix a few mandoc issues

- no blank before trailing delimiter
- whitespace at end of input line
- sections out of conventional order
- normalizing date format
- AUTHORS section without An macro

Regularize the Netflix copyright

Use recent best practices for Copyright form at the top of
the license:
1. Remove all the All Rights Reserved clauses on our stuff. Where we
piggybacked others, use a separate line to make things clear.
2. Use "Netflix, Inc." everywhere.
3. Use a single line for the copyright for grep friendliness.
4. Use date ranges in all places for our stuff.

Approved by: Netflix Legal (who gave me the form), adrian@ (pmc files)

Implement --hints to read hints file directly

In testing, it's often useful to copy a few files into a directory and
kldxref them to ensure that particular cases are handled correctly.
Add --hints (-h) to facilitate this testing and enable future
automated testing.

Sponsored by: Netflix

Add option to parse NOMATCH event and suggest modules to load

Add --nomatch/-p to search for individual drivers based on a NOMATCH
event from devd.

Submitted by: hps (earlier version)
Sponsored by: Netflix

devmatch.8: Link to MODULE_PNP_INFO(9)

Sponsored by: Dell EMC Isilon

Move devmatch to sbin from usr/sbin.

Since we want to use devmatch in context before a split /,/usr system
has mounted /usr, move devmatch to /sbin.

Sponsored by: Netflix