MFC r297183:

Use a SKIP testplan instead of bailing out if/when the tester isn't
root, or the geom class can't be loaded cleanly [*]

This makes sure that scenarios that are easy to hit aren't counted
as false positives with kyua test

PR: 208101

MFC r293821:

Integrate
tools/regression/geom_{concat,eli,gate,mirror,nop,raid3,shsec,stripe,uzip}
in to the FreeBSD test suite as
tests/sys/geom/class/{concat,eli,gate,mirror,nop,raid3,shsec,stripe,uzip}

The tools/regression/geom and tools/regression/geom_part testcases are being
left alone because both test sets are both currently broken.

The majority of this work was done on ^/user/ngie/more-tests2 . The differences
are as follows:
- tests/sys/geom/class/Makefile.inc is not present; it was
inlined into the class's Makefiles for explicitness.
- The testcases officially require root via kyua
- The geom_gate(4) tests don't use the pidfile changes proposed in
https://reviews.freebsd.org/D4836 .

Integrate
tools/regression/geom_{concat,eli,gate,mirror,nop,raid3,shsec,stripe,uzip}
in to the FreeBSD test suite as
tests/sys/geom/class/{concat,eli,gate,mirror,nop,raid3,shsec,stripe,uzip}

The tools/regression/geom and tools/regression/geom_part testcases are being
left alone because both test sets are both currently broken.

The majority of this work was done on ^/user/ngie/more-tests2 . The differences
are as follows:
- tests/sys/geom/class/Makefile.inc is not present; it was
inlined into the class's Makefiles for explicitness.
- The testcases officially require root via kyua
- The geom_gate(4) tests don't use the pidfile changes proposed in
https://reviews.freebsd.org/D4836 .

MFC after: 1 month
Sponsored by: EMC / Isilon Storage Division

- Move functions that might be used in class-specific cleanup functions
(geom_test_cleanup, etc) down so the testcases don't emit noise when
bailing
- Conform to the TAP protocol better when dealing with classes that can't
be loaded and with temporary files that can't be allocated for tracking
md(4) devices.

MFC after: 2 weeks
X-MFC with: r293028, r293029, r293048
Sponsored by: EMC / Isilon Storage Division

- Use a temporary file for the temporary md(4) devices instead of
hardcoding it
- Remove the temporary file in the cleanup routine

MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division

Add functions for managing md(4) devices and cleaning up said md(4) devices

These will be used soon in the various test scripts that source geom_subr.sh

MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division

- Use geom <class> load instead of g<class> load; g<class> doesn't exist
for all geom classes, e.g. geom_uzip(4)
- These tests require root. Skip all of the tests if they're run as non-root

MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division

Add file with helper functions for geom tools regression tests.